How to check if a PHP function exists?

In PHP, use the function_exists() function to check whether the function exists: it receives the function name parameter (string). Returns a Boolean value: true if the function exists, false if it does not exist.

#How to check if a PHP function exists?

In PHP, you can use the function_exists() function to check if a function exists. This function receives one parameter, the function name (in string form), and returns a Boolean value: true means the function exists, false means it does not exist.

Syntax:

bool function_exists ( string $function_name )

Parameters:

• $function_name - to be checked Function name (string)

Actual case:

<?php

// 检查是否存在 my_function 函数
if (function_exists('my_function')) {
    echo 'my_function 存在';
} else {
    echo 'my_function 不存在';
}

Output:

my_function 不存在

Because The my_function function has not been defined yet, so the output will be "my_function does not exist".

Note:

• Function names must be lowercase.
• If you use the __autoload() function to automatically load a function, you need to call this function before checking whether the function exists.
• You can also use the is_callable() function to check whether the function exists and is callable.

The above is the detailed content of How to check if a PHP function exists?. For more information, please follow other related articles on the PHP Chinese website!