Read STDIN (SYSIN) in COBOL

问题

I want to read the lines out of STDIN (aka SYSIN) in COBOL. For now I just want to print them out so that I know I've got them. From everything I'm reading it looks like this should work:

IDENTIFICATION DIVISION.
PROGRAM-ID. APP.

ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.

    SELECT SYSIN ASSIGN TO DA-S-SYSIN ORGANIZATION LINE SEQUENTIAL.

DATA DIVISION.
FILE SECTION.

FD SYSIN.
01 ln PIC X(255).
    88 EOF VALUE HIGH-VALUES.
WORKING-STORAGE SECTION.

PROCEDURE DIVISION.
    OPEN INPUT SYSIN
    READ SYSIN
      AT END SET EOF TO TRUE
    END-READ
    PERFORM UNTIL EOF
        DISPLAY ln
        READ SYSIN
            AT END SET EOF TO TRUE
        END-READ
    END-PERFORM
    CLOSE SYSIN
    STOP RUN.

That compiles (using open-cobol and cobc -x), but running it I get:

libcob: File does not exist (STATUS = 35) File : ''

What am I doing wrong?

回答1:

The following was suggested to me on the OpenCOBOL forums.

SELECT SYSIN ASSIGN TO KEYBOARD ORGANIZATION LINE SEQUENTIAL.

It's the keyword KEYBOARD that makes it work.

Apparently DISPLAY is a similar word for STDOUT, but I have not tested that.

回答2:

My COBOL dates back to the DPS-6 minicomputer runnong GCOS-6 and I lasted touched that in 1992. But back then we used ACCEPT to get input from stdin.

回答3:

You can just use the ACCEPT keyword to grab keyboard output. Loop through until you hit a keyword such as 'end', or you can use the hex value of EOF (1A, I believe).

As in:

1000-YOUR-PARAGRAPH.
  ACCEPT WS-YOUR-VARIABLE.
  DISPLAY WS-YOUR-VARIABLE.
  IF WS-YOUR-VARIABLE IS NOT EQUAL TO EOF
    THEN GO TO 1000-YOUR-PARAGRAPH
  ELSE GO TO 1090-EXIT
  END-IF.
1090-EXIT.
  EXIT.

That will take everything up to an EOL marker (e.g. return).

来源：https://stackoverflow.com/questions/938760/read-stdin-sysin-in-cobol

标签

select

stdin

cobol

sysin