How to check if a method exists in a given object in PHP?

In the previous article "Use 3 magical constants in PHP to quickly obtain the directory, file name and line number", I introduced to you the method of using 3 constants to obtain the current directory, file name and line number. Friends in need can find out!

So this article will introduce you to a very common question during the PHP interview process:

The question is like "How does PHP check whether a method in a given object exists?"

I’ll give you 3 seconds. Can you give me a quick answer?

Yes, it is the method_exists() function!

PHP method_exists() function is used to check whether the method in a given object exists. If you are asked about this basic knowledge in the interview, I believe you can definitely win it easily!

The following is a brief introduction to the use of the method_exists() function:

The syntax of this function is method_exists(objectname, methodname);

The parameter objectname represents the object example or class name.

The parameter methodname represents the method name.

Note: The parameters objectname and methodname are required fields.

Examples of using method_exists() are as follows:

<?php
    class Demo {
        function funcdemo(){
            echo &#39;Hello World&#39;;
        }
    }
    $demo = new Demo();
    if(method_exists($demo, funcdemo)) {
        echo &#39;方法存在于给定对象中&#39;;
    }
?>

Output:

方法存在于给定对象中

By the way, I would like to introduce some related functions:

→function_exists() - Returns true if the given function has been defined;

Syntax: function_exists(string $function_name): bool

Return value: If function_name exists and is indeed a function, it returns true , otherwise it returns false .

→is_callable() - Check whether the parameter is a legal callable structure;

Syntax: is_callable(callable $name, bool $syntax_only = false, string &$callable_name = ?): bool

Return value: true if name is callable, otherwise false.

→class_exists() - Check whether the class has been defined;

Syntax: class_exists(string $class, bool $autoload = true): bool

Return value: If the class pointed to by class has been defined, this function returns true, otherwise it returns false.

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