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/U, /u (Undefine Symbols)

/U[ ]symbol


The symbol you want undefined.


These options undefine previously defined symbols. /U undefines the specified symbol. /u undefines all previously defined symbols.

Neither option can undefine symbols created with the #define directive.

/u undefines the following Microsoft-specific macros. /U can undefine these options also.

Symbol Function
_CHAR_UNSIGNED Default char type is unsigned. Defined when /J is specified.
_CPPRTTI Defined for code compiled with the /GR (Enable Run-Time Type Information) option.
_CPPUNWIND Defined for code compiled with the /GX (Enable Exception Handling) option.
_DLL Defined when /MD is specified.
_M_IX86 1Defined as 500 for Blend (/GB), 300 for 80386 (/G3), 400 for 80486 (/G4), 500 for Pentium (/G5), and 600 for Pentium Pro, Pentium II, and Pentium III (/G6).
_MSC_VER See Predefined Macros for more information.
_WIN32 1Defined for applications for WIN32. Always defined.
_MT Defined when /MD or /MT is specified.

1   x86 specific

To set this compiler option in the Visual Studio development environment

  1. Open the project's Property Pages dialog box. For details, see Setting Visual C++ Project Properties.
  2. Click the C/C++ folder.
  3. Click the Advanced property page.
  4. Modify the Undefine Preprocessor Definitions or Undefine All Preprocessor Definitions properties.

To set this compiler option programmatically

See UndefineAllPreprocessorDefinitions Property or UndefinePreprocessorDefinitions Property.

See Also

Compiler Options | Setting Compiler Options