/U, /u (Undefine Symbols)
The /U compiler option undefines the specified preprocessor symbol. The /u compiler option undefines the Microsoft-specific symbols that the compiler defines.
Neither the /U or /u option can undefine a symbol created by using the #define directive.
The /U option can undefine a symbol that was previously defined by using the /D option.
By default, the compiler defines the following Microsoft-specific symbols.
Default char type is unsigned. Defined when the /J option is specified.
Defined for code compiled with the /GR option.
Defined for code compiled with the /EHsc option.
Defined when the /MD option is specified.
By default, defined to 600 for x86 targets.
For more information, see Predefined Macros.
Defined for WIN32 applications. Always defined.
Defined when the /MD or /MT option is specified.
To set this compiler option in the Visual Studio development environment
Open the project's Property Pages dialog box. For details, see How to: Open Project Property Pages.
Click the C/C++ folder.
Click the Advanced property page.
Modify the Undefine Preprocessor Definitions or Undefine All Preprocessor Definitions properties.