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The TRACE Macro

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This topic explains how to use the TRACE macro during development to print or display debugging messages from a program. TRACE prints a string argument to your debugger.

Note   With 32-bit MFC, the only way to get debug output is via the debugger.

The TRACE macro can handle a variable number of arguments, similar to the way printf operates. Following are examples of different ways to use TRACE macros:

int x = 1;
int y = 16;
float z = 32.0;
TRACE( "This is a TRACE statement\n" );

TRACE( "The value of x is %d\n", x );

TRACE( "x = %d and y = %d\n", x, y );

TRACE( "x = %d and y = %x and z = %f\n", x, y, z );

The TRACE macro is active only in the debug version of the class library. After a program has been debugged, you can build a release version to deactivate all TRACE calls in the program.

Tip   When debugging Unicode, the TRACE0, TRACE1, TRACE2, and TRACE3 macros are easier to use because the _T macro is not needed.

For important information on the TRACE macro, see in the Class Library Reference and .