How to reverse text in php

How to achieve text reversal in php: 1. Use the strrev function to achieve the reversal; 2. Reverse by dividing the string into an array, and then traverse and splice it; 3. Use recursion to achieve the reversal change.

The operating environment of this article: windows7 system, PHP7.1 version, DELL G3 computer

How to reverse text in php?

Three ways to reverse strings in php

(Assume there is a string abcd, use php to reverse the string)

1. The first type of php has its own function strrev that can be easily implemented:

$str = 'abcd';
//第一种自带strrev实现翻转
echo strrev($str);

Output effect:

2. Just split the string into one array, and then traverse and splice:

function joinStrrev($str){
        if (strlen($str) <= 1) return $str;

        $newstr  = &#39;&#39;;
        //str_split(string,length) 函数把字符串分割到数组中:string 必需。规定要分割的字符串。length     可选。规定每个数组元素的长度。默认是 1。
        $strarr = str_split($str,1);
        foreach ($strarr as $word) {
            $newstr = $word.$newstr;
        }
 
        return $newstr;
    }

$revstr = joinStrrev($str);
echo $revstr;

Output effect:

3. Just use recursion to do it:

function recursionStrrev($str){        if (strlen($str) <= 1) return $str;//递归出口         $newstr = &#39;&#39;;        //递归点，substr(string,start,length) ：substr() 函数返回字符串的一部分，如果 start 参数是负数且 length 小于或等于 start，则 length 为 0，正数 - 在字符串的指定位置开始，负数 - 在从字符串结尾的指定位置开始，0 - 在字符串中的第一个字符处开始        $newstr .= substr($str,-1).recursionStrrev(substr($str,0,strlen($str)-1));         return $newstr;//递归出口    }    $revstr = recursionStrrev($str);    echo $revstr;

Output effect:

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