PHP截取字符串

PHP截取字符串，用函数截取字符串的专题，支持UTF-8、GB2312、GBK多种字符集。
截取GB2312中文字符串

<?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; 
} 
?>

截取utf8编码的多字节字符串 

<?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); 
} 
?> 

UTF-8、GB2312都支持的汉字截取函数 

<?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’);  
?>

PHP字符截取函数

<?php 
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 = "phpq.net-- 简单、精彩、通用";  
$Length = "18";  
$Append = false;  
echo sysSubStr($String,$Length,$Append);  
?>