What is the use of php __toString() method

"__toString()" is a magic method in PHP, which is automatically called when converting an object into a string. It is used for how a class should respond when it is treated as a string; this method must return a string , otherwise a fatal error of "E_RECOVERABLE_ERROR" level will be issued.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

__toString(), the class is treated as The response method for string

__toString() is a magic method in PHP that is automatically called when converting an object into a string.

In object-oriented programming, PHP provides a series of magic methods, which provide a lot of convenience for programming and play a very important role in PHP. Magic methods in PHP usually start with __ (two underscores) and do not need to be explicitly called but are automatically called under certain conditions.

Function:

__toString() method is used for how a class should respond when it is treated as a string. For example what `echo $obj;` should display.

Note:

This method must return a string, otherwise a fatal error of level `E_RECOVERABLE_ERROR` will be issued.

Warning:

Cannot throw exceptions in the __toString() method. Doing so will result in a fatal error.

Code:

<?php
class Person
{
    public $sex;
    public $name;
    public $age;
    public function __construct($name="",  $age=25, $sex=&#39;男&#39;)
    {
        $this->name = $name;
        $this->age  = $age;
        $this->sex  = $sex;
    }
    public function __toString()
    {
        return  &#39;go go go&#39;;
    }
}
$person = new Person(&#39;小明&#39;); // 初始赋值
echo $person;

Result:

go go go

So what happens if there is no __toString() magic method in the class? Let’s test it:

Code:

<?php
class Person
{
    public $sex;
    public $name;
    public $age;
    public function __construct($name="",  $age=25, $sex=&#39;男&#39;)
    {
        $this->name = $name;
        $this->age  = $age;
        $this->sex  = $sex;
    }
    
}
$person = new Person(&#39;小明&#39;); // 初始赋值
echo $person;

Result:

Catchable fatal error: Object of class Person could not be converted to string in D:\phpStudy\WWW\test\index.php on line 18
很明显，页面报了一个致命错误，这是语法所不允许的。

Extended information: The magic methods in PHP are as shown in the following table:

Magic method	Function
__construct()	Automatically called when instantiating a class
__destruct()	Automatically called when the class object is used
__set()	in Automatically called when assigning a value to an undefined property
__get()	Automatically called when calling an undefined property
__isset()	Automatically called when using isset() or empty() function
__unset()	Automatically called when using unset()
__sleep()	Automatically called when serializing using serialize
__wakeup()	Use unserialize Automatically called when deserializing
__call()	Automatically called when calling a non-existent method
__callStatic( )	Automatically called when calling a non-existent static method
__toString()	Automatically called when converting an object into a string
__invoke()	Automatically called when trying to call an object as a method
__set_state()	When Automatically called when using the var_export() function, accepting an array parameter
__clone()	Automatically called when using clone to copy an object
__debugInfo()	Use var_dump() to automatically call when printing object information

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