/U, /u (Undefine Symbols)
The latest version of this topic can be found at -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.
Syntax
/U[ ]symbol
/u
Arguments
symbol
The preprocessor symbol to undefine.
Remarks
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.
| Symbol | Function |
|---|---|
| _CHAR_UNSIGNED | Default char type is unsigned. Defined when the /J option is specified. |
| _CPPRTTI | Defined for code compiled with the /GR option. |
| _CPPUNWIND | Defined for code compiled with the /EHsc option. |
| _DLL | Defined when the /MD option is specified. |
| _M_IX86 | By default, defined to 600 for x86 targets. |
| _MSC_VER | For more information, see Predefined Macros. |
| _WIN32 | Defined for WIN32 applications. Always defined. |
| _MT | 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.
To set this compiler option programmatically
See Also
Compiler Options
Setting Compiler Options
/J (Default char Type Is unsigned)
/GR (Enable Run-Time Type Information)
/EH (Exception Handling Model)
/MD, /MT, /LD (Use Run-Time Library)