PHP 截取字符串专题

1. 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;
}
?>

2. 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);
}
?>
3.
UTF-8、GB2312都支持的汉字截取函数

< ?php

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

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;
    }
}
echo sysSubStr("CodeBit.cn --
简单、精彩、通用",18,false);
?>