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This article will introduce to you the detailed usage of PHP object-oriented __toString(). The __toString() method is automatically called when directly outputting an object reference
As we said before, the method of declaring the method name starting with "--" in the class (provided to us by PHP) is a method that is automatically called and executed under different circumstances at a certain time. The "__toString()" method is also automatically The one that is called is automatically called when the object reference is output directly. We mentioned earlier that the object reference is a pointer. For example, in "$p=new Person()", $p is a reference. We cannot use echo directly. Output $p, which will output an error like "Catchable fatal error: Object of class Person could not be converted to string". If you define the "__toString()" method in the class, when you directly output the object reference, No error will be generated, but the "__toString()" method is automatically called to output the characters returned in the "__toString()" method, so the "__toString()" method must have a return value (return statement).
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It seems familiar. In the magic method __set of PHP object-oriented programming, I once introduced what a magic method is. This chapter also introduces a magic method __tostring().
__toString() is a convenient way to quickly obtain the string information of an object. It seems that magic methods have an "automatic" feature, such as automatic acquisition, automatic printing, etc. __toString() is no exception. It directly outputs the object reference. Automatically called method.
The function of __toString()
When we debug a program, we need to know whether we are getting the correct data. For example, when printing an object, see what attributes the object has and what their values are. If the class defines the toString method, you can echo print the object body during testing, and the object will automatically call the toString method defined by the class it belongs to. , format and output the data contained in this object.
Let’s look at an example of __toString()
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02 class Person{ 03 private $name = ""; |
07 }
15 }