PHP object-oriented-detailed code examples of tostring() and invoke()

Mar 27, 2017 am 10:06 AM

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:

&lt;?php
ini_set(&#39;display_errors&#39;, 1);
class A{
    public $name;    
    public $age;   
     public $sex;    
     function construct($name, $age, $sex){
        $this-&gt;name = $name;        
        $this-&gt;age = $age;        
        $this-&gt;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 = &quot;abc&quot; . $obj1;  //.为字符串连接符，会报错
$v2 = &quot;abx&quot; + $obj1;  //+为加法运算符，会报错?&gt;

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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

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The tostring() method is defined in the class

&lt;?php
ini_set(&#39;display_errors&#39;, 1);
class A{
    public $name;    
    public $age;    
    public $sex;    
    function construct($name, $age, $sex){
        $this-&gt;name = $name;        
        $this-&gt;age = $age;        
        $this-&gt;sex = $sex;   
    }    function tostring(){
        $str = &quot;姓名：&quot; . $this-&gt;name;   
        $str .= &quot;年龄：&quot; . $this-&gt;age;    
        $str .= &quot;，性别：&quot; . $this-&gt;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?&gt;

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Running result

姓名：张三年龄：15，性别：男

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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 &quot;&lt;br /&gt;我是一个对象呀，你别把我当作一个函数来调用啊！&quot;;
    }
}$obj = new A();$obj();    //此时就会调用类中的方法：invoke()

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