Q105043: Maximum Number of Bytes Read Using Low-Level Functions

Article: Q105043
Product(s): Microsoft FoxPro
Version(s): MS-DOS:2.0,2.5,2.5a; WINDOWS:2.5,2.5a,3.0
Operating System(s): 
Keyword(s): kberrmsg
Last Modified: 05-FEB-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
- Microsoft FoxPro for MS-DOS, versions 2.0, 2.5, 2.5a 
- Microsoft FoxPro for Windows, versions 2.5, 2.5a 
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SUMMARY
=======

When you are using FoxPro low-level functions to read a file, the maximum number
of bytes that can be read in is 65,535. If this number is exceeded, error
message #11 "Invalid function argument value, type or count" will be generated.

MORE INFORMATION
================

The number of bytes read is for a single command only, which means a file of
greater size can be read but the number of bytes read at one time can not exceed
65,535. This can be demonstrated with the following example. After the error
message is generated, the user may choose Ignore to continue with the program
execution.

     mchan=FOPEN("C:\any_large_file",12)
     ? FREAD(mchan,65536)
     *error message number 11 generated
     ? FGETS(mchan,65536)
     *error message number 11 generated
     ? FREAD(mchan,65535)
     * or
     ? FGETS(mchan,65535)
     * no error is generated
     ? FCLOSE(mchan)

Additional query words: VFoxWin FoxDos FoxWin errmsg err msg

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Keywords          : kberrmsg 
Technology        : kbVFPsearch kbAudDeveloper kbFoxproSearch kbZNotKeyword3 kbFoxPro200DOS kbFoxPro250DOS kbFoxPro250aDOS kbFoxPro250 kbFoxPro250a kbVFP300
Version           : MS-DOS:2.0,2.5,2.5a; WINDOWS:2.5,2.5a,3.0

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