The function_exists() is an inbuilt function in PHP. The function_exists() function is useful in case if we want to check whether a function() exists or not in the PHP script. It is used to check for both built-in functions as well as user-defined functions.
Parameter: This function accepts a single parameter $function_name. This is the name of function that we want to search in the list of defined function. This is a string type parameter.
Return Values: This function returns a Boolean value. In case a function with the name $function_name exists it returns TRUE, otherwise it returns FALSE. This function will also return FALSE for constructs like “include_once”, “echo” etc.
Below programs illustrate the function_exists() function in PHP:
in_array() function is available.
WelcomeMsg() function is available.
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