The difference between pass by value and pass by reference PHP

php value passing: Within the function scope, changing the variable value will not affect the variable value outside the function.

php by reference: Within the scope of the function, any changes to the value are also reflected outside the function, because the memory address is passed by reference.

Explanation with examples:

Passing value: It is the same as copy. [For example, I have a house. I give you building materials. You build a house that is exactly the same as mine. Whatever you do in your house will not affect me. What I do in my house will not affect me. Nothing will affect you, independent of each other. 】

<?php    
$testa=1;               //定义变量a 
$testb=2;               //定义变量b    
$testb = $testa;       //变量a赋值给变量b    
echo $testb;            //显示为1    
?>

Passing by reference: Similar to pointers in C language, it feels almost the same. For example, I have a house. If I give you a key, both of us can enter the house. Whatever you do in the house will affect me.

<?php    
$param2=1;               //定义变量2    
$param1 = &$param2;      //将变量2的引用传给变量1    
echo $param2;            //显示为1    
$param1 = 2;             //把2赋值给变量1    
echo $param2;            //显示为2    
?>

Advantages and Disadvantages: Passing values ​​will be time-consuming, especially for large strings and objects, this will be a very expensive operation, transferring references, functions Any operation within is equivalent to the operation of the transferred variable, and it is efficient when transferring large variables!

Recommended video tutorial: PHP video tutorial

The above is the detailed content of The difference between pass by value and pass by reference PHP. For more information, please follow other related articles on the PHP Chinese website!