Code example of method returning reference type in php

Reference of php (that is, adding the & symbol in front of a variable, function, object, etc.) //The most important thing is to delete the variable referenced by , but the referenced variable cannot be accessed. But the content is not destroyed. The meaning of reference in PHP is: different names access the same variable content.

This article mainly introduces the method of returning reference type in PHP,

<?php
 
$color = &#39;YellowGreen&#39;;
 
function &getRef() {
    global $color;
    return $color;
}
 
function getCopy() {
    global $color;
    return $color;
}
 
$colorRef = &getRef();
$colorRef = &#39;Blue&#39;;
 
//$colorCopy = getCopy();
//$colorCopy = &#39;Black&#39;;
 
 
var_dump($color);
var_dump($colorRef);
//var_dump($colorCopy);

Run the above code once, and you will almost understand that using &getRef() will bind $colorRef to $color, which means that $colorRef and $color variables point to Same value. When you change one of the values, the other will also change.

If $color is an array, the same is true. The above code will behave behavior the same in any version of PHP4/5.

The problem arises when $color is an Object.

In PHP4, getCopy will still return a copied Object; &getRef() returns a reference.

PHP5 is a bit different,
The latest PHP5.2 behaves the same as PHP4, getCopy() returns copy, &getRef() returns reference.
But some PHP5 versions are slightly different here, such as PHP5.1.6, which shows that getCopy() and &getRef() are both references.

Here getCopy() and &getRef() are two global functions. If they are placed in a class and become member functions of the class, it will be another story...

PS: Returning References will not improve performance, but sometimes it will reduce performance, so don't take it for granted to use this feature to "optimize" the program.

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