Dictionary.net

A programming technique that prevents a section ofcode from being executed by putting it in an if statementwhose condition is always false.It is often easier to do this than to comment out the codebecause you don't need to modify the code itself (as you would ifcommenting out each line individually) or worry about nestedcomments within the code (as you would if putting nesting commentdelimiters around it).For example, in Perl you could write: if (0) ...code to be ignored... In a compiled language, the compiler could simply generate nocode for the whole if statement. Some compiled languages such asC provide compile-time directives that achieve the same effect,e.g.: #if 0 ...code to be ignored... #endif(or "#ifdef notdef").