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Q155196: HOWTO: Use #pragma to Generate User-Defined Warning Messages

Article: Q155196
Product(s): Microsoft C Compiler
Version(s): WIN3X:1.5,1.51,1.52;WINNT:2.0,2.1,2.2,4.0,4.1,4.2,5.0
Operating System(s): 
Keyword(s): kbide kbLangC kbVC100 kbVC150 kbVC151 kbVC152 kbVC200 kbVC210 kbVC220 kbVC400 kbVC410 k
Last Modified: 04-AUG-2001

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The information in this article applies to:

- Microsoft Visual C++, versions 1.0, 1.5, 1.51, 1.52, 2.0, 2.1, 2.2, 4.0, 4.1 
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SUMMARY
=======

In some instances, you may find it advantageous to have the compiler generate
user-defined warning messages such as the following:

  collisions.cpp(1) : Warning Msg: Need to do 3-D collision checking

When such a warning is generated by the compiler and displayed in the Developer
Studio's Output window, you can double-click on the warning message to get to
the line of code with the message.

MORE INFORMATION
================

The following code illustrates how to use the #pragma message to force the
compiler to generate the above warning message. Note the spacing around the
colons in the third #define statement. The Visual Workbench that ships with the
16-bit versions of Visual C++ does not recognize a double-click in the Output
window unless the proper spacing exists between the colons.

  // collisions.h
  #define __STR2__(x) #x
  #define __STR1__(x) __STR2__(x)
  #define __LOC__ __FILE__ "("__STR1__(__LINE__)") : Warning Msg: "

  // collisions.cpp
  #pragma message(__LOC__"Need to do 3D collision testing")

REFERENCES
==========

For additional information concerning the #pragma message directive, see the
Visual C++ Help file; Search on: "message (pragma directive)."

For additional information concerning the __FILE__ and __LINE__ predefined
macros, see the Visual C++ Help file; Search on: "predefined macros," Topic:
"Preprocessor Reference," and click on "ANSI."

Additional query words:

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Keywords          : kbide kbLangC kbVC100 kbVC150 kbVC151 kbVC152 kbVC200 kbVC210 kbVC220 kbVC400 kbVC410 kbVC420 kbVC500 kbVC600 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbvc150 kbvc100 kbVC220 kbVC410 kbVC420 kbVC500 kbVC600 kbVC151 kbVC200 kbVC210 kbVC32bitSearch kbVC152 kbVC500Search
Version           : WIN3X:1.5,1.51,1.52;WINNT:2.0,2.1,2.2,4.0,4.1,4.2,5.0
Issue type        : kbhowto

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