php字符串截取（UTF-8/GB2312）

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1. 截取GB2312中文字符串
<?php
< ?php 
//截取中文字符串
function mysubstr($str, $start, $len) {
    $tmpstr = "";
    $strlen = $start + $len;
    for($i = 0; $i < $strlen; $i++) {
        if(ord(substr($str, $i, 1)) > 0xa0) {
            $tmpstr .= substr($str, $i, 2);
            $i++;
        } else
            $tmpstr .= substr($str, $i, 1);
    }
    return $tmpstr;
}
?>
2. 截取utf8编码的多字节字符串
<?php
< ?php
//截取utf8字符串
function utf8Substr($str, $from, $len)
{
    return preg_replace('#^(?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'.$from.'}'.
                       '((?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'.$len.'}).*#s',
                       '$1',$str);
}
?>
3. UTF-8、GB2312都支持的汉字截取函数
<?php
< ?php
/* 
Utf-8、gb2312都支持的汉字截取函数 
cut_str(字符串, 截取长度, 开始长度, 编码); 
编码默认为 utf-8 
开始长度默认为 0 
*/ 
 
function cut_str($string, $sublen, $start = 0, $code = 'UTF-8') 
{ 
    if($code == 'UTF-8') 
    { 
        $pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/"; 
        preg_match_all($pa, $string, $t_string); 
 
        if(count($t_string[0]) - $start > $sublen) return join('', array_slice($t_string[0], $start, $sublen))."...";
        return join('', array_slice($t_string[0], $start, $sublen)); 
    } 
    else 
    { 
        $start = $start*2; 
        $sublen = $sublen*2; 
        $strlen = strlen($string); 
        $tmpstr = ''; 
 
        for($i=0; $i< $strlen; $i++) 
        { 
            if($i>=$start && $i< ($start+$sublen)) 
            { 
                if(ord(substr($string, $i, 1))>129) 
                { 
                    $tmpstr.= substr($string, $i, 2); 
                } 
                else 
                { 
                    $tmpstr.= substr($string, $i, 1); 
                } 
            } 
            if(ord(substr($string, $i, 1))>129) $i++; 
        } 
        if(strlen($tmpstr)< $strlen ) $tmpstr.= "..."; 
        return $tmpstr; 
    } 
} 
 
$str = "abcd需要截取的字符串"; 
echo cut_str($str, 8, 0, 'gb2312'); 
?>
4. BugFree 的字符截取函数
<?php
< ?php 
/** 
 * @package     BugFree 
 * @version     $Id: FunctionsMain.inc.php,v 1.32 2005/09/24 11:38:37 wwccss Exp $ 
 * 
 * 
 * Return part of a string(Enhance the function substr()) 
 * 
 * @author                  Chunsheng Wang <wwccss@263.net> 
 * @param string  $String  the string to cut. 
 * @param int     $Length  the length of returned string. 
 * @param booble  $Append  whether append "...": false|true 
 * @return string           the cutted string. 
 */ 
function sysSubStr($String,$Length,$Append = false) 
{ 
    if (strlen($String) < = $Length ) 
    { 
        return $String; 
    } 
    else 
    { 
        $I = 0; 
        while ($I < $Length) 
        { 
            $StringTMP = substr($String,$I,1); 
            if ( ord($StringTMP) >=224 ) 
            { 
                $StringTMP = substr($String,$I,3); 
                $I = $I + 3; 
            } 
            elseif( ord($StringTMP) >=192 ) 
            { 
                $StringTMP = substr($String,$I,2); 
                $I = $I + 2; 
            } 
            else 
            { 
                $I = $I + 1; 
            } 
            $StringLast[] = $StringTMP; 
        } 
        $StringLast = implode("",$StringLast); 
        if($Append) 
        { 
            $StringLast .= "..."; 
        } 
        return $StringLast; 
    } 
} 
 
$String = "CodeBit.cn -- 简单、精彩、通用"; 
$Length = "18"; 
$Append = false; 
echo sysSubStr($String,$Length,$Append); 
?>