# 07-keybreak-summary — Key Break Summary

## 电信业务场景

加入者月汇总。按客户ID进行key切汇总，计算每位客户当月的通话总量和总金额。输出每个客户的汇总记录。

Demonstrates the classic COBOL control-break (key break) pattern:

- Read sorted input file grouped by KEY
- Compare WS-PREV-KEY to detect key change
- On key change: write summary (KEY, COUNT, TOTAL) and reset accumulators
- At end-of-file: write final group summary
- Accumulate grand total across all groups

## Files

| File | Purpose |
|------|---------|
| `main-07-keybreak-summary.cbl` | COBOL program (fixed format) |
| `data-gen.sh` | Generate sorted test data |
| `run.sh` | Compile, run, verify output |

## Input Record

| Field | Type | Length |
|-------|------|--------|
| KEY | PIC X | 10 |
| AMOUNT | PIC 9 | 10 |

## Output Record

| Field | Type | Notes |
|-------|------|-------|
| KEY | PIC X(10) | Group key |
| COUNT | PIC Z(5)9 | Record count in group |
| TOTAL | PIC Z(9)9 | Sum of AMOUNT in group |