PHP function_exists() returns false for empty()

Question

Why does function_exists("empty")return false?

if (function_exists("empty")) {
    echo "Not working";
}

Documentation states the following for function_exists:

Checks the list of defined functions, both built-in (internal) and user-defined, for function_name.

As far as I know empty is a defined and built-in function.

This is where reading the actual PHP docs helps: empty() is not a function, it is a language construct — Mark Baker
– Mark Baker, Commented Aug 14, 2014 at 10:12

Community · Accepted Answer · 2023-11-17 20:13:27Z

5

Empty is not a function. According to manual:

Note: Because this is a language construct and not a function, it cannot be called using variable functions.

https://www.php.net/manual/en/function.empty.php

edited Nov 17, 2023 at 20:13

CommunityBot

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answered Aug 14, 2014 at 10:11

phuk

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3 Comments

lawls Over a year ago

Is there any way to check if it exists?

lawls Over a year ago

@MarkBaker Of course, but I'm writing a validation class that can take any php function and execute it with a specfied value. So I have to check that the function exists...

Steini Over a year ago

@lawls Consider using call_user_func() or call_user_func_array() in this case, it will return === false in case the function does not exist.

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