Q25950

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page	Q25950: CodeView Versions 2.10 to 2.30 Use Four Extra File Handles	/pubs/pc/reference/microsoft/kb/Q25950/

Q25950: CodeView Versions 2.10 to 2.30 Use Four Extra File Handles

Article: Q25950
Version(s): 2.30 2.20 2.10 2.00
Operating System: MS-DOS
Flags: ENDUSER |
Last Modified: 19-JAN-1990

Problem:

CodeView Versions 2.00 to 2.30 seem to be using four additional file
handles. The following program attempts to open 20 files, reporting
its success or failure after each attempt:

    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>

    main()
    {
            FILE *streams[20];
            int i;
            char buffer[12];
            char *p;

            for (i = 0; i < 20; i++) {
                    p = itoa(i, buffer, 10);
                    p = strcat(buffer, ".dat");
                    streams[i] = fopen(buffer, "w+");
                    printf("streams[%d] = %d\n", i, streams[i]);
            }
    }

Running outside of CodeView, the call to fopen() fails after 15
streams have been opened. Running in CodeView Versions 1.x, the call
fails after 15 files have been opened. However, in CodeView Versions
2.00 to 2.30, it fails after 11 file handles have been opened.

Response:

CodeView Versions 2.00 to 2.30 require four file handles for their own
use. Remember that MS-DOS itself has five preopened file handles. If
you want to open more than 15 files, follow the steps specified in the
C Version 5.10 README.DOC to modify the C start-up code to allow
opening more than 20 files.