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< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 声明一个整型变量，取名为 a< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > a;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 给变量赋值< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > a < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 10< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " a = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , a);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < / div > < / div > < ul > < li > 示例：初始化（声明变量的同时给其赋值）< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 声明一个整型变量，取名为 b ，并直接赋值（初始化，实际开发中最为常用）< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > b < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 200< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 修改变量 b 的值，将变量 a 的值赋值给变量 b< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > b < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 300< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " b= < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , b);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < / div > < / div > < ul > < li > 示例：同时声明多个变量并赋值< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 同时声明多个整型的变量并赋值< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > c1 < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 10< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , c2 < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 20< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , c3 < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 30< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " c1 = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , c1);< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " c2 = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , c2);< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " c3 = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , c3);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
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< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < / div > < / div > < h2 id = "_1-4-输出变量" tabindex = "-1" > 1.4 输出变量 < a class = "header-anchor" href = "#_1-4-输出变量" aria-label = "Permalink to "1.4 输出变量"" > < / a > < / h2 > < ul > < li > 在计算机中，所谓的< code > 输入< / code > 和< code > 输出< / code > 都是以计算机（ < / li > < / ul > < div class = "note custom-block github-alert" > < p class = "custom-block-title" > NOTE< / p > < p > < / p > < p > 输入：从输入设备(键盘、鼠标、扫描仪)向计算机输入数据。< / p > < p > 输出：从计算机向外部输出设备(显示器、打印机)输出数据。< / p > < / div > < p > < img src = "/c/assets/3.XcPl7d9s.png" alt = "" > < / p > < ul > < li > 在 C 语言中，提供了 < code > printf()< / code > 函数用于输出信息，其函数声明是：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > const< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > char< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#E36209;--shiki-dark:#FFAB70;" > __format< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , ...) {< / span > < / span >
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< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ...< / span > < / span >
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< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < / div > < / div > < ul > < li > < code > printf< / code > 的标准含义是格式化输出文本，来源于 < code > print formatted（ ） < / code > 的缩写，其语法规则，如下所示：< / li > < / ul > < p > < img src = "/c/assets/4.DL02VQMp.png" alt = "" > < / p > < div class = "note custom-block github-alert" > < p class = "custom-block-title" > NOTE< / p > < p > < / p > < ul > < li > 格式化字符串：是使用双引号括起来的字符串，里面包含了普通的字符串和格式占位符。< / li > < li > 格式占位符（格式声明符）：由 < code > %< / code > 和< code > 格式字符< / code > 组成，作用是将输出的数据转换为指定的格式后输出，这里的 < code > %d< / code > 表示整数。< / li > < li > 输出列表：是程序要输出的一些数据，可以是常量、变量或表达式，需要和格式占位符一一对应。< / li > < / ul > < / div > < ul > < li > < p > 在计算机中，二进制、八进制、十进制以及十六进制的英文名称和缩写，如下所示：< / p > < ul > < li > 二进制（ ） ， < / li > < li > 八进制（ ） ， < / li > < li > 十进制（ ） ， < / li > < li > 十六进制（ ） ， < / li > < / ul > < / li > < li > < p > 其实，我们也可以在 Windows 系统中的计算器中来看到，即：< / p > < / li > < / ul > < p > < img src = "/c/assets/5.Dr67r_Ws.png" alt = "" > < / p > < div class = "important custom-block github-alert" > < p class = "custom-block-title" > IMPORTANT< / p > < p > < / p > < p > 在生活中的 decimal 是小数的意思；但是，在 C 语言中， < / p > < / div > < ul > < li > 示例：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
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< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 声明变量并赋值< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 18< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 使用输出语句，将变量 num 的值输出，其中 %d 表示输出的是整数< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 我今年< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 岁< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > \n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < / div > < / div > < h2 id = "_1-5-输入数据赋值给变量" tabindex = "-1" > 1.5 输入数据赋值给变量 < a class = "header-anchor" href = "#_1-5-输入数据赋值给变量" aria-label = "Permalink to "1.5 输入数据赋值给变量"" > < / a > < / h2 > < ul > < li > 在 C 语言中，提供了 < code > scanf()< / code > 函数用于从标准输入（通常是键盘）中读取数据并根据变量的地址赋值给变量（变量需要提前声明），其函数声明是：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > scanf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > const< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > char< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#E36209;--shiki-dark:#FFAB70;" > __format< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , ...) {< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ...< / span > < / span >
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< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < / div > < / div > < ul > < li > 其语法规则，如下所示：< / li > < / ul > < p > < img src = "/c/assets/6.C5XiXNVN.png" alt = "" > < / p > < div class = "note custom-block github-alert" > < p class = "custom-block-title" > NOTE< / p > < p > < / p > < p > < code > & age< / code > 、< code > & num< / code > 中的 < code > & < / code > 是寻址操作符，< code > & age< / code > 表示变量 < code > age< / code > 在内存中的地址。< / p > < / div > < div class = "caution custom-block github-alert" > < p class = "custom-block-title" > CAUTION< / p > < p > < / p > < ul > < li > < p > ① scanf() 函数中的 < code > %d< / code > ，如果是连着写，即：< code > %d%d< / code > ，那么在输入数据的时候，数据之间不可以使用逗号< code > ,< / code > 分隔， （ < code > 2空格3tab< / code > 或< code > 2tab3回车< / code > 等。< / p > < / li > < li > < p > ② 如果是 < code > %d,%d< / code > ，则输入的时候需要加上逗号< code > ,< / code > ，即：< code > 2,3< / code > 。< / p > < / li > < li > < p > ③ 如果是 < code > %d %d< / code > ，则输入的时候需要加上空格，即：< code > 2空格3< / code > 。< / p > < / li > < / ul > < / div > < ul > < li > 示例：计算圆的面积，半径由用户指定< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
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< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > float< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 请输入一个半径：" < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > );< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > scanf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %f< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > & < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > double< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > area < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 3.1415926< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 半径是< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %f< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的圆的面积是< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %.2lf< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , radius, area);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < span class = "line-number" > 15< / span > < br > < / div > < / div > < ul > < li > 示例：输入一个整数值，求其绝对值< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 请输入一个整数：" < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > );< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > scanf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > & < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > absNum;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > if< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (num < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > < < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ) {< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > absNum < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > -< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > } < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > else< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > {< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > absNum < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的绝对值是：< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num, absNum);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < span class = "line-number" > 15< / span > < br > < span class = "line-number" > 16< / span > < br > < span class = "line-number" > 17< / span > < br > < span class = "line-number" > 18< / span > < br > < span class = "line-number" > 19< / span > < br > < span class = "line-number" > 20< / span > < br > < span class = "line-number" > 21< / span > < br > < / div > < / div > < ul > < li > 示例：输入多个变量的值，求其乘积< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > a, b, c;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 请输入整数 a 、b 和 c 的值：" < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > );< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > scanf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > & < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > a, < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > & < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > b, < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > & < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > c);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > result < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > a < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > b < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > c;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > × < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > × < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , a, b, c, result);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < / div > < / div > < h2 id = "_1-6-标识符" tabindex = "-1" > 1.6 标识符 < a class = "header-anchor" href = "#_1-6-标识符" aria-label = "Permalink to "1.6 标识符"" > < / a > < / h2 > < h3 id = "_1-6-1-概述" tabindex = "-1" > 1.6.1 概述 < a class = "header-anchor" href = "#_1-6-1-概述" aria-label = "Permalink to "1.6.1 概述"" > < / a > < / h3 > < ul > < li > 在 C 语言中，变量、函数、数组名、结构体等要素命名的时候使用的字符序列，称为标识符。< / li > < / ul > < div class = "note custom-block github-alert" > < p class = "custom-block-title" > NOTE< / p > < p > < / p > < p > 在上世纪 60 - 70 年代的时候，因为国家贫穷，人民生活不富裕等原因，家长虽然会给孩子取名为：< code > 张建国< / code > 、< code > 李华强< / code > 等；但是，也会取小名为< code > 二狗子< / code > 、< code > 狗剩< / code > 等，目的是希望孩子能健康成长（养活），像 < code > 张建国< / code > 、< code > 李华强< / code > 、< code > 二狗子< / code > 、< code > 狗剩< / code > 都是名字（标识符），伴随人的一生。< / p > < / div > < h3 id = "_1-6-2-标识符的命名规范" tabindex = "-1" > 1.6.2 标识符的命名规范 < a class = "header-anchor" href = "#_1-6-2-标识符的命名规范" aria-label = "Permalink to "1.6.2 标识符的命名规范"" > < / a > < / h3 > < ul > < li > < p > 强制规范：< / p > < ul > < li > ① 只能由< code > 小写< / code > 或< code > 大写英文字母< / code > ， < code > 0-9< / code > 或 < code > _< / code > 组成。< / li > < li > ② 不能以< code > 数字< / code > 开头。< / li > < li > ③ 不可以是< code > 关键字< / code > 。< / li > < li > ④ 标识符具有< code > 长度< / code > 限制，不同编译器和平台会有所不同，一般限制在 63 个字符内。< / li > < li > ⑤ 严格< code > 区分大小写字母< / code > ， ： < / li > < / ul > < / li > < li > < p > 建议规范：< / p > < ul > < li > ① 为了提高阅读性， ， ， ： ， ， ， < / li > < li > ② 使用下划线连接多个单词组成的标识符， ： < / li > < li > ③ 多个单词组成的标识符，除了使用下划线连接，也可以使用小驼峰命名法，除第一个单词外，后续单词的首字母大写，如： studentId、student_name 等。< / li > < li > ④ 不要出现仅靠大小写区分不同的标识符， ： < / li > < li > ⑤ 系统内部使用了一些下划线开头的标识符， ： < code > _Bool< / code > ，为防止冲突，建议开发者尽量避免使用下划线开头的标识符。< / li > < / ul > < / li > < li > < p > 示例：合法（不一定建议）的标识符< / p > < / li > < / ul > < div class = "language-txt vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > txt< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span > a、BOOK_sun、MAX_SIZE、Mouse、student23、Football、FOOTBALL、max、_add、num_1、sum_of_numbers< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < / div > < / div > < ul > < li > 示例：非法的标识符< / li > < / ul > < div class = "language-txt vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > txt< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span > $zj、3sum、ab#cd<63>
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 1< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > ' A' < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 12.3< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 你好" < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < / div > < / div > < ul > < li > 示例：字面量常量< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 整数常量 =》< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 1< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > );< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 字符常量 =》< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %c\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , < / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > ' A' < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > );< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 浮点数常量 =》< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %f\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 12.3< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > );< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 字符串常量 =》< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %s\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , < / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 你好" < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > );< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < / div > < / div > < h2 id = "_2-3-使用-define-定义常量" tabindex = "-1" > 2.3 使用 #define 定义常量 < a class = "header-anchor" href = "#_2-3-使用-define-定义常量" aria-label = "Permalink to "2.3 使用 #define 定义常量"" > < / a > < / h2 > < ul > < li > < code > #define< / code > 来定义常量，也叫作宏定义，就是用一个标识符来表示一个常量值，如果在后面的代码中出现了该标识符，那么编译时就全部替换成指定的常量值，即用宏体替换所有宏名，简称< code > 宏替换< / code > 。< / li > < li > 格式是：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > #define 常量名 常量值< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < / div > < / div > < div class = "caution custom-block github-alert" > < p class = "custom-block-title" > CAUTION< / p > < p > < / p > < ul > < li > ① 其实< code > 宏定义< / code > 的常量的< code > 执行时机< / code > 是在< code > 预处理< / code > 阶段，将所有< code > 宏常量< / code > 替换完毕，才会继续编译代码。< / li > < li > ② 不要以 < code > ;< / code > 结尾，如果有 < code > ;< / code > ，分号也会成为常量值的一部分。< / li > < li > ③ < code > # define< / code > 必须写在 < code > main< / code > 函数的外面！！！< / li > < li > ④ < code > 常量名< / code > 习惯用< code > 大写字母< / code > 表示，如果多个单词，使用 < code > _< / code > 来分隔，以便和变量区分。< / li > < / ul > < / div > < ul > < li > 示例：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #define< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > PI< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 3.1415926< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > double< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 2.5< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > double< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > area < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > PI < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 半径为< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %lf< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的圆的面积是< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %.2lf< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , radius, area);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < / div > < / div > < h2 id = "_2-4-const-关键字" tabindex = "-1" > 2.4 const 关键字 < a class = "header-anchor" href = "#_2-4-const-关键字" aria-label = "Permalink to "2.4 const 关键字"" > < / a > < / h2 > < ul > < li > C99 标准新增，这种方式跟定义一个变量是类似的；只不过，需要在变量的数据类型前加上 < code > const< / code > 关键字。< / li > < li > 和使用 < code > #define定义宏常量< / code > 相比， < / li > < li > 格式是：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > const< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > 数据类型 常量名 < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > 常量值;< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < / div > < / div > < ul > < li > 示例：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > const< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > PI < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 3.1415926< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > double< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 2.5< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > double< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > area < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > PI < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > *< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > radius;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 半径为< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %lf< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的圆的面积是< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %.2lf< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , radius, area);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < / div > < / div > < h2 id = "_2-5-枚举常量" tabindex = "-1" > 2.5 枚举常量 < a class = "header-anchor" href = "#_2-5-枚举常量" aria-label = "Permalink to "2.5 枚举常量"" > < / a > < / h2 > < ul > < li > 格式：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > enum< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > 枚举常量 {< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > xxx < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 1< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > yyy;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ...< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < / div > < / div > < div class = "note custom-block github-alert" > < p class = "custom-block-title" > NOTE< / p > < p > < / p > < ul > < li > ① 默认情况下，枚举常量是从 0 开始递增的。< / li > < li > ② 也可以在定义枚举常量的时候，自定义它们的值。< / li > < / ul > < / div > < ul > < li > 示例：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > enum< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > sex {< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > MALE < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 1< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ,< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > FEMALE < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 2< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ,< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > };< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , MALE);< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , FEMALE);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < / div > < / div > < ul > < li > 示例：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > enum< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > Sex {< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > MALE < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 1< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ,< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > FEMALE < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 2< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ,< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > };< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > enum< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > Sex sex;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 请输入性别(1 表示男性, 2 表示女性)： " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > );< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > scanf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > & < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > sex);< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " 您的性别是：< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , sex);< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
2024-07-11 10:13:52 +02:00
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < span class = "line-number" > 15< / span > < br > < span class = "line-number" > 16< / span > < br > < / div > < / div > < h2 id = "_2-6-defind-定义常量-vs-const-定义常量" tabindex = "-1" > 2.6 #defind 定义常量 VS const 定义常量 < a class = "header-anchor" href = "#_2-6-defind-定义常量-vs-const-定义常量" aria-label = "Permalink to "2.6 #defind 定义常量 VS const 定义常量"" > < / a > < / h2 > < ul > < li > ① 执行时机：< code > #define< / code > 是预处理指令，在编译< code > 之前< / code > 执行；< code > const< / code > 是关键字，在编译< code > 过程< / code > 中执行。< / li > < li > ② 类型检查：< code > #define< / code > 定义常量< code > 不用指定类型< / code > ， < code > 不进行类型检查< / code > ，只是简单地文本替换；< code > const< / code > 定义常量< code > 需要指定数据类型< / code > ， < code > 会进行类型检查< / code > ，类型安全性更强。< / li > < / ul > < h1 id = "第三章-二进制" tabindex = "-1" > 第三章：二进制 < a class = "header-anchor" href = "#第三章-二进制" aria-label = "Permalink to "第三章：二进制"" > < / a > < / h1 > < h2 id = "_3-1-概述" tabindex = "-1" > 3.1 概述 < a class = "header-anchor" href = "#_3-1-概述" aria-label = "Permalink to "3.1 概述"" > < / a > < / h2 > < ul > < li > 计算机的底层只有< code > 二进制< / code > ，即计算机中< code > 运算< / code > 和< code > 存储< / code > 的< code > 所有数据< / code > 都需要转换为< code > 二进制< / code > ，包括：数字、字符、图片、视频等。< / li > < / ul > < p > < img src = "/c/assets/7.DO8XxSV6.jpg" alt = "" > < / p > < ul > < li > 之前，我们也提到现代的计算机（量子计算机除外）几乎都遵循< code > 冯·诺依曼< / code > 体系结构，其理论要点如下： < ul > < li > ① < strong > 存储程序< / strong > ： < code > 程序指令< / code > 和< code > 数据< / code > 都存储在计算机的内存中，这使得程序可以在运行时修改。< / li > < li > ② < strong > 二进制逻辑< / strong > ：所有数据和指令都以< code > 二进制< / code > 形式表示。< / li > < li > ③ < strong > 顺序执行< / strong > ：指令按照它们在内存中的顺序执行，但可以有条件地改变执行顺序。< / li > < li > ④ < strong > 五大部件< / strong > ：计算机由< code > 运算器< / code > 、< code > 控制器< / code > 、< code > 存储器< / code > 、< code > 输入设备< / code > 和< code > 输出设备< / code > 组成。< / li > < li > ⑤ < strong > 指令结构< / strong > ：指令由操作码和地址码组成，操作码指示要执行的操作，地址码指示操作数的位置。< / li > < li > ⑥ < strong > 中心化控制< / strong > ： （ ） ， < / li > < / ul > < / li > < li > 所以，再次论证了为什么计算机只能识别二进制。< / li > < / ul > < h2 id = "_3-2-进制" tabindex = "-1" > 3.2 进制 < a class = "header-anchor" href = "#_3-2-进制" aria-label = "Permalink to "3.2 进制"" > < / a > < / h2 > < h3 id = "_3-2-1-常见的进制" tabindex = "-1" > 3.2.1 常见的进制 < a class = "header-anchor" href = "#_3-2-1-常见的进制" aria-label = "Permalink to "3.2.1 常见的进制"" > < / a > < / h3 > < ul > < li > 在生活中，我们最为常用的进制就是< code > 十进制< / code > ，其规则是< code > 满 10 进 1< / code > ，即：< / li > < / ul > < p > < img src = "/c/assets/8.CUXrdefp.jpeg" alt = "" > < / p > < ul > < li > 在计算机中，常见的进制有< code > 二进制< / code > 、< code > 八进制< / code > 和< code > 十六进制< / code > ，即： < ul > < li > 二进制：只能 0 和 1 ，满 2 进 1 。< / li > < li > 八进制： ，
2024-07-11 10:07:44 +02:00
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num1 < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > 0b< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 10100110< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 二进制< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num2 < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > 0< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 717563< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 八进制< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num3 < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 1000< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 十进制< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num4 < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > 0x< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > af72< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 十六进制< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " num1 = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num1);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // num1 = 166< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " num2 = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num2);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // num2 = 237427< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " num3 = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num3);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // num3 = 1000< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " num4 = < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num4);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // num4 = 44914< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < span class = "line-number" > 15< / span > < br > < span class = "line-number" > 16< / span > < br > < / div > < / div > < h3 id = "_3-2-3-输出格式" tabindex = "-1" > 3.2.3 输出格式 < a class = "header-anchor" href = "#_3-2-3-输出格式" aria-label = "Permalink to "3.2.3 输出格式"" > < / a > < / h3 > < ul > < li > 在 C 语言中，可以使用不同的< code > 格式占位符< / code > 来< code > 输出< / code > 不同< code > 进制< / code > 的整数，如下所示： < ul > < li > < code > %d< / code > ：十进制整数。< / li > < li > < code > %o< / code > ：八进制整数。< / li > < li > < code > %x< / code > ：十六进制整数。< / li > < li > < code > %#o< / code > ：显示前缀 < code > 0< / code > 的八进制整数。< / li > < li > < code > %#x< / code > ：显示前缀 < code > 0x< / code > 的十六进制整数。< / li > < li > < code > %#X< / code > ：显示前缀 < code > 0X< / code > 的十六进制整数。< / li > < / ul > < / li > < / ul > < div class = "caution custom-block github-alert" > < p class = "custom-block-title" > CAUTION< / p > < p > < / p > < p > C 语言中没有输出二进制数的格式占位符！！！< / p > < / div > < ul > < li > 示例：< / li > < / ul > < div class = "language-c vp-adaptive-theme line-numbers-mode" > < button title = "Copy Code" class = "copy" > < / button > < span class = "lang" > c< / span > < pre class = "shiki shiki-themes github-light github-dark vp-code" tabindex = "0" > < code > < span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > #include< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > < stdio.h> < / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > main< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > () {< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > int< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > num < / span > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > =< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 100< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的十进制整数： < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num, num);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 100 的十进制整数： 100< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的八进制整数： < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %o\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num, num);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 100 的八进制整数： 144< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的十六进制整数： < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %x\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num, num);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 100 的十六进制整数： 64< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的八进制（前缀）整数： < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %#o\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num, num);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 100 的八进制（前缀）整数： 0144< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的十六进制（前缀）整数： < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %#x\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num, num);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 100 的十六进制（前缀）整数： 0x64< / span > < / span >
< span class = "line" > < span style = "--shiki-light:#6F42C1;--shiki-dark:#B392F0;" > printf< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > (< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %d< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > 的十六进制（前缀）整数： < / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > %#X\n< / span > < span style = "--shiki-light:#032F62;--shiki-dark:#9ECBFF;" > " < / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > , num, num);< / span > < span style = "--shiki-light:#6A737D;--shiki-dark:#6A737D;" > // 100 的十六进制（前缀）整数： 0X64< / span > < / span >
< span class = "line" > < / span >
< span class = "line" > < span style = "--shiki-light:#D73A49;--shiki-dark:#F97583;" > return< / span > < span style = "--shiki-light:#005CC5;--shiki-dark:#79B8FF;" > 0< / span > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > ;< / span > < / span >
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< span class = "line" > < span style = "--shiki-light:#24292E;--shiki-dark:#E1E4E8;" > }< / span > < / span > < / code > < / pre > < div class = "line-numbers-wrapper" aria-hidden = "true" > < span class = "line-number" > 1< / span > < br > < span class = "line-number" > 2< / span > < br > < span class = "line-number" > 3< / span > < br > < span class = "line-number" > 4< / span > < br > < span class = "line-number" > 5< / span > < br > < span class = "line-number" > 6< / span > < br > < span class = "line-number" > 7< / span > < br > < span class = "line-number" > 8< / span > < br > < span class = "line-number" > 9< / span > < br > < span class = "line-number" > 10< / span > < br > < span class = "line-number" > 11< / span > < br > < span class = "line-number" > 12< / span > < br > < span class = "line-number" > 13< / span > < br > < span class = "line-number" > 14< / span > < br > < span class = "line-number" > 15< / span > < br > < / div > < / div > < h2 id = "_3-3-进制的转换" tabindex = "-1" > 3.3 进制的转换 < a class = "header-anchor" href = "#_3-3-进制的转换" aria-label = "Permalink to "3.3 进制的转换"" > < / a > < / h2 > < h3 id = "_3-3-1-概述" tabindex = "-1" > 3.3.1 概述 < a class = "header-anchor" href = "#_3-3-1-概述" aria-label = "Permalink to "3.3.1 概述"" > < / a > < / h3 > < ul > < li > 不同进制的转换，如下所示：< / li > < / ul > < p > < img src = "/c/assets/9.uqLiL_yu.png" alt = "" > < / p > < ul > < li > 在计算机中，数据是从右往左的方式排列的；其中，最右边的是低位，最左边的是高位，即：< / li > < / ul > < p > < img src = "/c/assets/10.CkykpHY2.png" alt = "" > < / p > < h3 id = "_3-3-2-二进制和十进制的转换" tabindex = "-1" > 3.3.2 二进制和十进制的转换 < a class = "header-anchor" href = "#_3-3-2-二进制和十进制的转换" aria-label = "Permalink to "3.3.2 二进制和十进制的转换"" > < / a > < / h3 > < h4 id = "_3-3-2-1-二进制转换为十进制" tabindex = "-1" > 3.3.2.1 二进制转换为十进制 < a class = "header-anchor" href = "#_3-3-2-1-二进制转换为十进制" aria-label = "Permalink to "3.3.2.1 二进制转换为十进制"" > < / a > < / h4 > < ul > < li > 规则：从最低位开始，将每个位上的数提取出来，乘以 2 的 （位数 - 1 ）次方，然后求和。< / li > < / ul > < div class = "note custom-block github-alert" > < p class = "custom-block-title" > NOTE< / p > < p > < / p > < ul > < li > ① 在学术界，将这种计算规则，称为< code > 位权相加法< / code > 。< / li > < li > ② < code > 八进制转换为十进制< / code > 、< code > 十六进制转换为十进制< / code > 和< code > 二进制转换为十进制< / code > 的算法相同！！！< / li > < / ul > < / div > < ul > < li > 示例：十进制转十进制< / li > < / ul > < p > < img src = "/c/assets/11.DV1YbrOP.png" alt = "" > < / p > < ul > < li > 示例：二进制转十进制< / li > < / ul > < p > < img src = "/c/assets/12.AHNJT9TV.png" alt = "" > < / p > < h4 id = "_3-3-2-2-十进制转换二进制" tabindex = "-1" > 3.3.2.2 十进制转换二进制 < a class = "header-anchor" href = "#_3-3-2-2-十进制转换二进制" aria-label = "Permalink to "3.3.2.2 十进制转换二进制"" > < / a > < / h4 > < ul > < li > 规则：将该数不断除以 2 ，直到商为 0 为止，然后将每步得到的余数倒过来，就是对应的二进制。< / li > < / ul > < div class = "note custom-block github-alert" > < p class = "custom-block-title" > NOTE< / p > < p > < / p > < ul > < li > ① 在学术界，将这种计算规则，称为< code > 短除法< / code > 或< code > 连续除2取余法< / code > 。< / li > < li > ② 很好理解，只有不断地除以 2 ，就能保证最大的数字不超过 2 ，这不就是二进制（只能有 0 或 1） ？ < / li > < li > ③ < code > 八进制转换为二进制< / code > 、< code > 十六进制转换为二进制< / code > 和< code > 十进制转换为二进制< / code > 的算法相同！！！< / li > < / ul > < / div > < ul > < li > 示例：十进制转十进制< / li > < / ul > < p > < img src = "/c/assets/13.Bs-MOwx2.png" alt = "" > < / p > < ul > < li > 示例：十进制转二进制< / li > < / ul > < p > < img src = "/c/assets/14.StzjmBz-.png" alt = "" > < / p > < h3 id = "_3-3-3-二进制转八进制" tabindex = "-1" > 3.3.3 二进制转八进制 < a class = "header-anchor" href = "#_3-3-3-二进制转八进制" aria-label = "Permalink to "3.3.3 二进制转八进制"" > < / a > < / h3 > < ul > < li > < p > 规则：每 3 位二进制就是一个八进制。< / p > < / li > < li > < p > 示例： > 351< / p > < / li > < / ul > < p > < img src = "/c/assets/15.C0wVWaxD.pn
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