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  • php字符串长度、翻转、比较、查找、替换

    //1、字符串长度
    function strlen($str)   { 
        if ($str == '') return 0; 
        $count = 0; 
        while (1){ 
            if ($str[$count] != NULL){ 
                $count++; 
                continue; 
            }else{ 
                break; 
            } 
        } 
        return $count; 
    } 
    
    
    //2、字符串翻转
    function strrev($str)   {   
        if ($str == '') return 0;   
        for ($i=(strlen($str)-1); $i>=0; $i--){      
            $rev_str .= $str[$i];   
        }   
        return $rev_str; 
    } 
    
    
    //3、字符串比较
    function strcmp($s1, $s2)   { 
        if (strlen($s1) < strlen($s2)) return -1; 
        if (strlen($s1) > strlen($s2)) return 1; 
        for ($i=0; $i<strlen($s1); $i++){ 
            if ($s1[$i] == $s2[$i]){ 
                continue; 
            }else{          
                return false; 
            }   
        }   
        return 0; 
    } 
    
    
    //4、查找字符串
    function strstr($str, $substr)  { 
        $m = strlen($str); 
        $n = strlen($substr); 
        if ($m < $n) return false; 
        for ($i=0; $i<=($m-$n+1); $i++){ 
            $sub = substr($str, $i, $n); 
            if (strcmp($sub, $substr) == 0) return $i; 
        } 
        return false; 
    } 
    
    
    //5、字符串替换
    function str_replace($substr, $newsubstr, $str) { 
        $m = strlen($str); 
        $n = strlen($substr); 
        $x = strlen($newsubstr); 
        if (strchr($str, $substr) == false) return false; 
        for ($i=0; $i<=($m-$n+1); $i++){ 
            $i = strchr($str, $substr); 
            $str = str_delete($str, $i, $n); 
            $str = str_insert($str, $i, $newstr); 
        } 
        return $str; 
    } 
    
    
    //6、插入一段字符串
    function str_insert($str, $i, $substr)  { 
        for($j=0; $j<$i; $j++){ 
            $startstr .= $str[$j]; 
        } 
        for ($j=$i; $j<strlen($str); $j++){ 
            $laststr .= $str[$j]; 
        } 
        $str = ($startstr . $substr . $laststr); 
        return $str; 
    } 
    
    
    //7、删除一段字符串
    function str_delete($str, $i, $j){  
        for ($c=0; $c<$i; $c++){ 
            $startstr .= $str[$c]; 
        } 
        for ($c=($i+$j); $c<strlen($str); $c++){ 
            $laststr .= $str[$c]; 
        } 
        $str = ($startstr . $laststr); 
        return $str; 
    } 
    
    
    //8、复制字符串
    function strcpy($s1, $s2){ 
        if (strlen($s1)==NULL || !isset($s2)) return; 
        for ($i=0; $i<strlen($s1); $i++){ 
            $s2[] = $s1[$i]; 
        } 
        return $s2; 
    } 
    
    
    //9、连接字符串
    function strcat($s1, $s2){ 
        if (!isset($s1) || !isset($s2)) return; 
        $newstr = $s1; 
        for($i=0; $i<count($s); $i++){ 
            $newstr .= $st[$i]; 
        } 
        return $newsstr; 
    } 
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  • 原文地址:https://www.cnblogs.com/seanpan/p/13993336.html
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