ILE C/C++ Compiler Reference

#undef (Undefining a Macro)

The preprocessor undef directive causes the preprocessor to end the scope of a preprocessor definition.

The undef directive has the form:

>>-#--undef--identifier----------------------------------------><
 
 

If the identifier is not currently defined as a macro, undef is ignored.

Example: #undef directive

The following directives define BUFFER and SQR:

#define BUFFER 512
#define SQR(x) ((x) * (x))

The following directives nullify these definitions:

#undef BUFFER
#undef SQR

Any occurrences of the identifiers BUFFER and SQR that follow these undef directives are not replaced with any replacement tokens. Once the definition of a macro has been removed by an undef directive, the identifier can be used in a new define directive.


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