Use #if 0 rather than comments to temporarily kill blocks of code. Non-portable example: int foo() { ... a = b + c; /* * Not doing this right now. a += 87; if (a > b) (* have to check for the candy factor *) c++; */ ... } This is a bad idea, because you always end up wanting to kill code blocks that include comments already. No, you can't rely on comments nesting properly. That's far from portab..