几个好用的截取字符串的php函数分享

分享几个好用的PHP 截取字符串函数(支持gb2312和utf-8)。

1、截取GB2312字符用的函数

<?php 
/**
**截取中文字符串 
* edit by www.jbxue.com
**/
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
* edit by www.jbxue.com
*/
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 
/* 
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 
* by www.jbxue.com
*/

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 
/** 
* @package BugFree 
* 
* 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 $Append whether append "...": false|true 
* @return string the cutted string. 
* @by www.jbxue.com
*/ 
function sysSubStr($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 = "book.chinaz.com -- 站长书库、站长教程"; 
$Length = "18"; 
$Append = false; 
echo sysSubStr($String,$Length,$Append); 
?>