Reference in php foreach Loop

This article introduces the reference problem analysis and precautions in the php foreach loop. I hope this article will be helpful to you.

Example

The Code is as follows:	Copy code
<? Php $ Array = array ('A', 'B', 'C', 'D '); Foreach ($ array as $ key => $ val ){ // Do something } Echo $ val; // Output d Echo $ kay; // output 3 $ Val = 'E '; Print_r ($ array); // output Array ([0] => a [1] => B [2] => c [3] => d) ?>

In a foreach loop, $ key and $ val variables are not automatically released after the loop ends. The value is retained.

When foreach is referenced, the following situations may occur.

The Code is as follows:	Copy code
<? Php $ Array = array ('A', 'B', 'C', 'D '); Foreach ($ array as $ key =>&$ val) {// use reference // Do something } Echo $ val; // Output d Echo $ kay; // output 3 $ Val = 'E '; Print_r ($ array); // output Array ([0] => a [1] => B [2] => c [3] => e) ?>

When the $ val variable is used and referenced, after the foreach loop is executed, $ val points to the same memory address as $ arrar [3.
After the foreach loop ends, the $ val variable still exists. Therefore, changing the value of $ val after the foreach loop ends is equivalent to changing the value of $ arrar [3.