#if 1 == 0 // The code in here will not be compiled since 1 doesn't equal 0 #endifFull Example use. Lets say you have:
int main() { obsoleteFunction(); /* Do not call this * function because its obsolete */ }You can comment it out with:
int main() { #if 1 == 0 obsoleteFunction(); /* Do not call this * function because its obsolete */ #endif }