Javascript debugger
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function_exists
Return TRUE if the given function has been defined
(PHP 4, PHP 5)
bool function_exists ( string function_name )
Return Values
Returns TRUE if function_name exists and is a
function, FALSE otherwise.
Note:
This function will return FALSE for constructs, such as
include_once() and echo().
Examples
Example 761. function_exists() example
<?php
if (function_exists('imap_open')) {
echo "IMAP functions are available.<br />\n";
} else {
echo "IMAP functions are not available.<br />\n";
}
?>
Notes
Note:
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).