Maximum Number of Bytes Read Using Low-Level Functions

ID: Q105043

2.00 2.50 2.50a | 2.50 2.50a 3.00

MS-DOS          | WINDOWS

• Microsoft Visual FoxPro for Windows, version 3.0
• Microsoft FoxPro for MS-DOS, versions 2.0, 2.5, and 2.5a
• Microsoft FoxPro for Windows, versions 2.5 and 2.5a

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)

Keywords          : kberrmsg FxprgGeneral 
Version           : 2.00 2.50 2.50a | 2.50 2.50a 3.0
Platform          : MS-DOS WINDOWS