PHP 截取字符串 分别适合GB2312和UTF8编码情况

<?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;
}
?>

<?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);
}
?>

<?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
/**
* @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 <[email]wwccss@263.net[/email]>
* @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 = "www.at0915.cn";
$length = "18";
$append = false;
echo syssubstr($string,$length,$append);
?>