Creating A Line Sequential File; Valid I/O Statements For Sequential Files - Compaq COBOL AAQ2G1FTK User Manual

Example 6–23 Creating a Line Sequential File
By default, Compaq COBOL assumes sequential access mode when the line
sequential organization is specified. (See Example 6–23.)
Statements for Sequential and Line Sequential File Processing
Processing a sequential or line sequential file involves the following:
1. Opening the file
2. Processing the file with valid I/O statements
3. Closing the file
Table 6–3 lists the valid I/O statements for sequential files, and Table 6–4 lists
the valid I/O statements for line sequential files. Both tables illustrate the
following relationships:
• Organization determines valid access modes.
• Organization and access mode determine valid open modes.
• All three (organization, access, and open mode) enable or disable I/O
statements.
Table 6–3 Valid I/O Statements for Sequential Files
File Access
Organization Mode
SEQUENTIAL SEQUENTIAL
Writing a Sequential File
Each WRITE statement appends a logical record to the end of an output file,
thereby creating an entirely new record in the file. The WRITE statement
appends records to files that are OPEN for the following modes:
IDENTIFICATION DIVISION.
PROGRAM-ID. LINESEQ01.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT LINESEQ-FILE ASSIGN TO "LINESEQ.DAT".
DATA DIVISION.
FILE SECTION.
FD LINESEQ-FILE.
01 LINESEQ-RECORD PIC X(25).
PROCEDURE DIVISION.
A000-BEGIN.
OPEN OUTPUT LINESEQ-FILE.
CLOSE LINESEQ-FILE.
STOP RUN.
Statement INPUT
READ Yes
REWRITE No
WRITE No
UNLOCK Yes
Processing Files and Records
6.3 Creating and Processing Files
Open Mode
OUTPUT I/O EXTEND
No Yes No
No Yes No
Yes No Yes
Yes Yes Yes
Processing Files and Records 6–27