The difference between passing by value and passing by reference in php

This article mainly introduces the difference between passing values ​​and passing references in calling PHP. It has certain reference value. Now I share it with everyone. Friends in need can refer to it

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 function scope, any changes to the value are also reflected outside the function, because The reference passed is the memory address.

#Daniel’s explanation:

Passing value : 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. I will do it in mine. Whatever happens in the house will not affect you, they are independent of each other. 】

#[php]

view plain copy

<?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    
?>

Pass 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]

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copy

<?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    
?>

1. ##[Advantages and Disadvantages:] Passing values ​​will be time-consuming. Especially for large strings and objects, this will be a very expensive operation. Transferring references. Any operation within the function is equivalent to the operation of transferring variables. Transferring large variables is efficient!

##Please indicate the source for reprinting https://blog.csdn.net/qq_28194557/article/details/70543753

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