What is the difference between is_a() function and instanceof in PHP?

The functions of the is_a() function and instanceof operator in PHP are similar, so what are the differences between them? The following article will give you a brief understanding of the is_a() function and instanceof, and introduce the difference between the is_a() function and instanceof. I hope it will be helpful to you. [Video tutorial recommendation: PHP tutorial]

##PHP is_a() function

is_a() function is a built-in function in PHP that checks whether a given object belongs to a given class; it also checks whether the given class is one of the parent classes of the given object.

Basic syntax:

is_a( $object, $class_name, $allow_string )

Parameters: is_a() function can accept the following three parameters

●Object: Use to save the test object.

●Class_name: used to save the class name.

● Allow_string: If the set value is False, string class names are not allowed to be used as objects.

Return value: If the object belongs to the given class, or this class is one of its parent classes, the is_a() function returns True, otherwise it returns a False value.

Let’s learn about the is_a() function through code examples.

<?php  
class hello {  
    var $store = &#39;Hello PHP!&#39;;  
}  
    
$PHP= new hello();  
    
// 检查$PHP是否是hello类的对象
if (is_a($PHP, &#39;hello&#39;)) {  
    echo "Yes";  
}  
    
?>

Output:

Yes

PHP instanceof operator

Use instanceof operator in PHP to find out whether an object Is an instantiated instance of a class.

Basic syntax:

$a instanceof MyClass

Operands: The instanceof operator contains the following two operands

● $a: represents the object.

●　MyClass: Indicates a class name.

Return value: If the object belongs to the given class, or this class is one of its parent classes, it returns True, otherwise it returns a False value.

Let’s learn about the instanceof operator through code examples.

<?php  
class hello {  
    var $store = &#39;Hello PHP!&#39;;  
}  
    
$PHP= new hello();  
    
// 检查$PHP是否是hello类的对象
if ($PHP instanceof hello) {  
    echo "Yes";  
}  
?>

Output:

Yes

The difference between is_a() function and instanceof operator

● is_a() is a function, and instanceof is a language structure. The is_a() function will be significantly slower since it has all the overhead of performing a function call.

●In the case of function callbacks (such as array_map), because instanceof is not a function, it is a language construct, so it cannot be used as a callback. However, callbacks can be used in the is_a() function.

●The usage time of the direct class name in InstanceOf is shorter than that of the is_a() function.

Example:

//语法短（比较）
$a instanceof MyClass
is_a( $a, MyClass::class )

●is_a() is a function that takes an object as parameter 1 and a string as parameter 2, while instanceof takes an object as parameter 1 and can Pass a class name, object instance, or class identifier (class name without quotes) as argument 2.

Example of is_a():

//只有这样才能调用它
is_a($object，$string);

instanceof example:

//对象实例      
$object instanceof $otherObject; 
//字符串类名
$object instanceof $string;
//类的标识符
$object instanceof ClassName;

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