function_exists

bool function_exists(string function_name)

Determines whether a function is defined.

Returns:

TRUE if the function exists; FALSE otherwise

Description:

function_exists() is used to determine whether the given function is defined in the current PHP environment.

Availability:

UNIX, Windows

Version:

3.0.7+, 4+

See also:

To find out whether a given method or class is defined:

method_exists() 
class_exists()

Example:

Find out whether a function exists
$function_name = 'get_big_raise'; 

if (function_exists ($function_name)) 
    print "Function <tt>$function_name</tt> exists (and there was much rejoicing)."; 
else 
    print "Function <tt>$function_name</tt> does not exist.";

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