Examples of Features and Uses of Reference Types and Value Types in PHP

This article illustrates the functions and usage of reference types and value types in PHP. Share it for your reference, as follows:

The four simple types in PHP and the complex type array are all value types. Inter-type assignment passes a value, that is, creates a copy to a new variable.

For example:

$int1 = 123;
$int2 = $int1;// What you pass directly is the value, just doing 1 A man named int1 The copy of is called int2
$int2 = 456;
echo $int1;// Output  123
echo $int1 === $int2;// Be false 
$int1 = 123;
$int2 = &$int1;// Take the address character and pass a reference 
$int2 = 456;
echo $int1;// Output  456
echo $int1 === $int2;// Output  1. Is true 

Objects are of reference type, and the default is to pass a reference, that is, the new variable is an alias of the old variable.

class Person{
    public $name;
}
$p1 = new Person();
$p1->name = 'Sheldon';
$p2 = $p1;
$p2->name = 'Leonard';
echo $p1->name;// Output: Lenoard
echo $p1 === $p2;// Output: 1  I.e. congruence  

If you want to get a copy of the object (which copies all the properties of the old variable) so that they do not affect each other, you can use the clone keyword.

class Person {
    public $name;
}
$p1 = new Person();
$p1->name = 123;
$p2 = clone $p1;
echo $p2->name;// Output  123
$p2->name = 456;
echo $p1->name;// Output  123

More readers interested in PHP can check out the topics of this site: "Introduction to php Object-Oriented Programming", "Encyclopedia of PHP Array (Array) Operation Skills", "Introduction to PHP Basic Grammar", "Summary of PHP Operation and Operator Usage", "Summary of php String (string) Usage", "Introduction to php+mysql Database Operation" and "Summary of php Common Database Operation Skills"

I hope this article is helpful to everyone's PHP programming.