PHP object-oriented-detailed code examples of __tostring() and __invoke()

tostring()Magic method

When an object is used as a string, it will This method is automatically called, and in this method, a certain string can be returned to indicate the result of converting the object into a string. This magic method is relatively common.
Note: If this method is not defined, the object cannot be used as a string!

Example of undefined tostring() method in class:

<?php
ini_set(&#39;display_errors&#39;, 1);
class A{
    public $name;    
    public $age;   
     public $sex;    
     function construct($name, $age, $sex){
        $this->name = $name;        
        $this->age = $age;        
        $this->sex = $sex;   
    }
}
$obj1 = new A(&#39;张三&#39;, 15, &#39;男&#39;);
echo $obj1;    //echo 后面为字符串，而对象不是字符串，会报错
$v1 = "abc" . $obj1;  //.为字符串连接符，会报错
$v2 = "abx" + $obj1;  //+为加法运算符，会报错?>

The three error contents are

Catchable fatal error: Object of class A could not be converted to string
Catchable fatal error: Object of class A could not be converted to string
Notice: Object of class A could not be converted to int

The tostring() method is defined in the class

<?php
ini_set(&#39;display_errors&#39;, 1);
class A{
    public $name;    
    public $age;    
    public $sex;    
    function construct($name, $age, $sex){
        $this->name = $name;        
        $this->age = $age;        
        $this->sex = $sex;   
    }    function tostring(){
        $str = "姓名：" . $this->name;   
        $str .= "年龄：" . $this->age;    
        $str .= "，性别：" . $this->sex;        
        return $str;   //这里可以返回“任何字符串内容”

    }
}
$obj1 = new A(&#39;张三&#39;, 15, &#39;男&#39;);
echo $obj1;    //调用tostring(),不会报错?>

Running result

姓名：张三年龄：15，性别：男

invoke() magic method

This method will be called automatically when the object is used as a function. This is generally not recommended.

class A{
    function invoke(){
        echo "<br />我是一个对象呀，你别把我当作一个函数来调用啊！";
    }
}$obj = new A();$obj();    //此时就会调用类中的方法：invoke()

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