function_exists

function_exists -- Return TRUE if the given function has been defined

Description

bool function_exists ( string function_name)

Checks the list of defined functions , both built-in ( internal ) and user-defined , for function_name . מחזיר TRUE במקרה של הצלחה או FALSE במקרה של כישלון .




Note that a function name may exist even if the function itself is unusable due to configuration or compiling options (with the image functions being an example). Also note that function_exists() will return FALSE for constructs, such as include_once() and echo() .