How to reverse Chinese strings in PHP to avoid garbled characters

This article mainly introduces the method of realizing Chinese string reversal in PHP to avoid garbled characters. It has a certain reference value. Now I share it with you. Friends in need can refer to it

When the blogger was looking at PHP interview questions online today, he saw such a question, how to reverse a string. At that time, he thought there was a built-in function strrev. Can this function be implemented? I tried it later and found that this function can only reverse English characters, and will cause garbled characters in Chinese characters. The main reason is still a coding problem.

In PHP, utf-8 encoded Chinese is calculated as 3 bytes, and gb2312 is calculated as 2 bytes. Therefore, if you want to implement some functions of Chinese strings, you must first solve the encoding problem.

is_string()//判断参数是否为字符串，这个大家应该都知道
mb_check_encoding()//用来检查给定的字符串是否属于指定的编码
mb_strlen()//用来获取字符串长度
mb_substr()//用来截取字符串中的字符
krsort()//将数组按键名由大到小排序上述

Three functions starting with mb are used above. The functions starting with mb are used to process multi-byte strings, mainly to specify the string encoding.

mb_check_encoding() accepts two parameters. The first parameter should be a string, and the second parameter is to enter a Character encoding, and then determine whether the string belongs to this encoding, and return a bool value. If the second parameter is omitted, it defaults to the internal encoding, which can be viewed through mb_internal_encoding().

mb_strlen() has two parameters, the first is the string content, and the second is the encoding of the string.

mb_substr() has four parameters. The first is the content of the string to be intercepted, the second is the starting position of interception, and the third is The length of the interception, and the fourth is the encoding of the string (in this case, select utf-8, other encodings will not get the correct result).

The following is the complete code. The brief comments have been marked. In fact, just look at You can understand it in one go:

<?php
    header("Content-type:text/html;charset=utf-8");
    $s="这是我的技术博客，欢迎多多来访！";
                              
    function str_rev($str){
        //先判断参数是否为字符串，且为UTF8编码
        if(!is_string($str)||!mb_check_encoding($str,"utf-8")){
            die("输入的不是utf8类型的字符串");
        }
                                  
        //用mb_strlen函获取算utf8字符串的长度
        $length=mb_strlen($str,"utf-8");
                                  
        //声明一个数组备用
        $arr=array();
                                  
        //将字符串拆开放入数组
        for($i=0;$i<$length;$i++){
            $arr[$i]=mb_substr($str,$i,1,"utf-8");
        }
                                  
        //将数组按键名大小反转
        krsort($arr);
                                  
        //将数组中单个字符元素重新组合成字符串
        $str=implode("",$arr);
                                  
        //将翻转后的字符串返回
        return $str;
    }
                              
    echo $s."<br>";
    echo str_rev($s);
/*  得到结果：
 *  这是我的技术博客，欢迎多多来访！
 *  ！访来多多迎欢，客博术技的我是这
 */

如果文中有任何错误，敬请指出，以便完善。

本文来自：http://5655237.blog.51cto.com/5645237/1258300

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