U
Undefines any definition currently in
effect for the specified
macro
.
Syntax
Linux:
-U
name
Windows:
/U
name
Arguments
- name
- Is the name of themacroto be undefined.
Default
- OFF
- Macrodefinitions are in effect until they are undefined.
Description
This option undefines any definition currently in effect
for the specified
macro
.
It is equivalent to
an #undef preprocessing directive.
On Windows systems, use the
/u
option to undefine all
previously defined preprocessor values.
IDE Equivalent
Visual Studio:
Preprocessor > Undefine
Preprocessor Definitions
Eclipse:
Preprocessor > Undefine
Preprocessor Definitions
Alternate Options
None
Example
To undefine a macro, enter the following command:
On Windows systems:
icx /Uia64 prog1.cpp
On Linux systems:
icpx -Uia64 prog1.cpp
If you attempt to undefine an ANSI C macro, the
compiler will emit an error:
invalid macro undefinition: <name of macro>