Commenting out code with the preprocessorThis tip submitted by Webmaster on 2005-01-24 14:16:39. It has been viewed 41556 times.
Rating of 5.7 with 193 votes
Because C and C++ do not allow nesting comments with /* and */, it can be a hassle to comment out long regions of code.
For instance, you cannot do this:
/* First layer /* Second layer */ */
because the first */ closes the entire comment!
Fortunately, the preprocessor can help you: you can use the #if .. #endif combination to cause the preprocessor to avoid compiling any portion of your code by using a condition that will never be true.
#if 0 /* comment */ /* code */ /* comment */ #endif
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