How to use for Loop in php

This article mainly shows you "how to use the for loop in php", the content is simple and clear, hoping to help you solve your doubts, the following let the editor lead you to study and learn "how to use the for loop in php" this article.

For cycle

/ / normal for ($I = 0; $I

< count($arr); $i++){ //}//优化一for($i = 0, $len = count($arr); $i < $len; $i++){ //}//优化二for($i = count($arr) - 1; $i >

-1;-- $I) {/}

Optimization 1: the problem is that the conditional judgment has to calculate the length of the array each time, so it is better to declare a variable to be stored in the first place. For loops in other languages are probably the same.

Optimization 2: you can save a $len variable without the need to grow from small to large. And then there is this small optimization-- $I is faster than $imure.

Conclusion: it is not necessarily good to optimize the second. I just thought of this and wrote it out. However, a good for cycle I think we should at least pay attention to the optimization of this, in addition, $iTunes + can be changed to + $I!

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