U

Syntax

    -Uname 

Purpose
Undefines the identifier name defined by the compiler or by the -Dname option.

Notes
The -Uname option is not equivalent to the #undef preprocessor directive. It cannot undefine names defined in the source by the #define preprocessor directive. It can only undefine names defined by the compiler or by the -Dname option.

The identifier name can also be undefined in your source program using the #undef preprocessor directive.

The -Uname option has a higher precedence than the -Dname option.

Example
To compile myprogram.c so that the definition of the name COUNT, is nullified, enter:

xlC myprogram.c  -UCOUNT

For example if the option -DCOUNT=1000 is used, a source line #undefine COUNT is generated at the top of the source.

List of Compiler Options and Their Defaults
Options that Specify Preprocessor Options