FUNCTION Procedures Cannot Be Invoked in I/O Statements (33301)
This article was previously published under Q33301
SUMMARY
You should avoid invoking (or nesting) a FUNCTION procedure in a Basic
statement that performs output to a file. Instead, the returned value
of the FUNCTION procedure should be assigned to an intermediate
variable, and the intermediate variable can then be used in the I/O
statement. (A FUNCTION procedure is defined in a FUNCTION...END
FUNCTION block.)
This and other restrictions are described on Page 201 of the
"Microsoft QuickBasic 4.0: Basic Language Reference" manual for
versions 4.00 and 4.00b, as follows:
Because Basic may rearrange arithmetic expressions for greater
efficiency, avoid using FUNCTION procedures that change program
variables in arithmetic expressions. Also avoid using FUNCTION
procedures that perform I/O in I/O statements. Using FUNCTION
procedures that perform graphics operations in graphics statements
may also cause side effects.
The same restriction is mentioned on Page 201 of the "Microsoft Basic
Compiler 6.0: Basic Language Reference" for versions 6.00 and 6.00b
for MS OS/2 and MS-DOS. It is also mentioned on Page 146 of the
"Microsoft Basic 7.0: Language Reference" manual.
Please note that user-defined functions defined with the DEF FN
statement do not have the above restrictions.
| Modification Type: |
Minor |
Last Reviewed: |
1/9/2003 |
| Keywords: |
KB33301 |
|