复制代码 代码如下:
<?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 = "简明现代魔法 —— 专注于互联网主流的各种技术";
$length = "27";
$append = true;
echo sysSubStr($string,$length,$append);
// 输出
// 简明现代魔法 —— 专...
?>

截取GB2312中文字符串：
复制代码 代码如下:
<?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：
复制代码 代码如下:
<?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：
复制代码 代码如下:
<?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');
?>