COBOL中的文件处理动词

COBOL是一种用于商业应用开发的编程语言，处理大量数据文件是其主要特点之一。因此，COBOL中的文件处理动词非常重要。

下面是COBOL中常用的文件处理动词：

1. OPEN

OPEN是COBOL中用来打开文件的动词。它可以打开顺序文件、随机文件和索引文件，下面是一个简单的实例：

IDENTIFICATION DIVISION.
PROGRAM-ID. OPEN-FILE.
DATA DIVISION.
FILE SECTION.
FD MY-FILE.
01 MY-REC.
   02 MY-FIELD-1 PIC X(10).
   02 MY-FIELD-2 PIC 9(5).
WORKING-STORAGE SECTION.
01 WS-STATUS PIC X(2).
PROCEDURE DIVISION.
MAIN-PROC.
   OPEN INPUT MY-FILE.
   IF WS-STATUS <> '00'
      DISPLAY 'OPEN ERROR - STATUS CODE: ' WS-STATUS
   ELSE
      DISPLAY 'FILE OPENED SUCCESSFULLY'
   END-IF.
   CLOSE MY-FILE.

2. CLOSE

CLOSE是COBOL中用来关闭文件的动词。它可以关闭顺序文件、随机文件和索引文件，下面是一个简单的实例：

IDENTIFICATION DIVISION.
PROGRAM-ID. CLOSE-FILE.
DATA DIVISION.
FILE SECTION.
FD MY-FILE.
01 MY-REC.
   02 MY-FIELD-1 PIC X(10).
   02 MY-FIELD-2 PIC 9(5).
WORKING-STORAGE SECTION.
01 WS-STATUS PIC X(2).
PROCEDURE DIVISION.
MAIN-PROC.
   OPEN INPUT MY-FILE.
   IF WS-STATUS <> '00'
      DISPLAY 'OPEN ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   CLOSE MY-FILE.
   IF WS-STATUS <> '00'
      DISPLAY 'CLOSE ERROR - STATUS CODE: ' WS-STATUS
   ELSE
      DISPLAY 'FILE CLOSED SUCCESSFULLY'
   END-IF.
   STOP RUN.

3. READ

READ是COBOL中用来读取文件记录的动词。它可以读取顺序文件、随机文件和索引文件，下面是一个简单的实例：

IDENTIFICATION DIVISION.
PROGRAM-ID. READ-FILE.
DATA DIVISION.
FILE SECTION.
FD MY-SEQ-FILE.
01 MY-REC.
   02 MY-FIELD-1 PIC X(10).
   02 MY-FIELD-2 PIC 9(5).
WORKING-STORAGE SECTION.
01 WS-STATUS PIC X(2).
PROCEDURE DIVISION.
MAIN-PROC.
   OPEN INPUT MY-SEQ-FILE.
   IF WS-STATUS <> '00'
      DISPLAY 'OPEN ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   READ MY-SEQ-FILE INTO MY-REC.
   IF WS-STATUS <> '00'
      DISPLAY 'READ ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   DISPLAY 'MY-FIELD-1: ' MY-FIELD-1
           ' MY-FIELD-2: ' MY-FIELD-2.
   CLOSE MY-SEQ-FILE.
   STOP RUN.

4. WRITE

WRITE是COBOL中用来写入文件记录的动词。它可以写入顺序文件、随机文件和索引文件，下面是一个简单的实例：

IDENTIFICATION DIVISION.
PROGRAM-ID. WRITE-FILE.
DATA DIVISION.
FILE SECTION.
FD MY-SEQ-FILE.
01 MY-REC.
   02 MY-FIELD-1 PIC X(10).
   02 MY-FIELD-2 PIC 9(5).
WORKING-STORAGE SECTION.
01 WS-STATUS PIC X(2).
PROCEDURE DIVISION.
MAIN-PROC.
   OPEN OUTPUT MY-SEQ-FILE.
   IF WS-STATUS <> '00'
      DISPLAY 'OPEN ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   MOVE 'HELLO' TO MY-FIELD-1.
   MOVE 12345 TO MY-FIELD-2.
   WRITE MY-REC.
   IF WS-STATUS <> '00'
      DISPLAY 'WRITE ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   CLOSE MY-SEQ-FILE.
   STOP RUN.

5. REWRITE

REWRITE是COBOL中用来重写文件记录的动词。它只适用于随机文件和索引文件，下面是一个简单的实例：

IDENTIFICATION DIVISION.
PROGRAM-ID. REWRITE-FILE.
DATA DIVISION.
FILE SECTION.
FD MY-RAND-FILE.
01 MY-REC.
   02 MY-KEY PIC X(10).
   02 MY-FIELD-1 PIC X(10).
   02 MY-FIELD-2 PIC 9(5).
WORKING-STORAGE SECTION.
01 WS-STATUS PIC X(2).
PROCEDURE DIVISION.
MAIN-PROC.
   OPEN I-O MY-RAND-FILE.
   IF WS-STATUS <> '00'
      DISPLAY 'OPEN ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   READ MY-RAND-FILE KEY IS 'ABC123'.
   IF WS-STATUS <> '00'
      DISPLAY 'READ ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   REPLACE MY-FIELD-1 OF MY-REC WITH 'HELLO'.
   REPLACE MY-FIELD-2 OF MY-REC WITH 12345.
   REWRITE MY-REC.
   IF WS-STATUS <> '00'
      DISPLAY 'REWRITE ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   CLOSE MY-RAND-FILE.
   STOP RUN.

6. DELETE

DELETE是COBOL中用来删除文件记录的动词。它只适用于随机文件和索引文件，下面是一个简单的实例：

IDENTIFICATION DIVISION.
PROGRAM-ID. DELETE-FILE.
DATA DIVISION.
FILE SECTION.
FD MY-RAND-FILE.
01 MY-REC.
   02 MY-KEY PIC X(10).
   02 MY-FIELD-1 PIC X(10).
   02 MY-FIELD-2 PIC 9(5).
WORKING-STORAGE SECTION.
01 WS-STATUS PIC X(2).
PROCEDURE DIVISION.
MAIN-PROC.
   OPEN I-O MY-RAND-FILE.
   IF WS-STATUS <> '00'
      DISPLAY 'OPEN ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   READ MY-RAND-FILE KEY IS 'ABC123'.
   IF WS-STATUS <> '00'
      DISPLAY 'READ ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   DELETE MY-REC.
   IF WS-STATUS <> '00'
      DISPLAY 'DELETE ERROR - STATUS CODE: ' WS-STATUS
      STOP RUN
   END-IF.
   CLOSE MY-RAND-FILE.
   STOP RUN.

以上就是COBOL中的文件处理动词的基本介绍和示例代码，程序员可以根据需要选择合适的动词来操作文件。