Export (0) Print
Expand All
Expand Minimize
2 out of 3 rated this helpful - Rate this topic

/U, /u (Undefine Symbols)

Undefine previously defined symbols. /U undefines the specified symbol. /u undefines all previously defined symbols.

/U[ ]symbol

The symbol you want undefined.

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

Both options undefine the following Microsoft-specific macros.

Symbol Function


Default char type is unsigned. Defined when /J is specified.


Defined for code compiled with the /GR (Enable Run-Time Type Information) option.


Defined for code compiled with the /EHsc (Enable Exception Handling) option.


Defined when /MD is specified.


Defined to 600, by default, for x86 targets.


For more information, see Predefined Macros.


Defined for applications for WIN32. Always defined.


Defined when /MD or /MT is specified.

To set this compiler option in the Visual Studio development environment

  1. Open the project's Property Pages dialog box. For details, see How to: Open Project Property Pages.

  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

Did you find this helpful?
(1500 characters remaining)
Thank you for your feedback

Community Additions

© 2014 Microsoft. All rights reserved.