字符串截取是一個(gè)非常常見(jiàn)的編程任務(wù)，而往往帶中文的字符串截取會(huì)經(jīng)常用到。雖然不難，但是自己寫(xiě)函數(shù)實(shí)現(xiàn)又耗費(fèi)時(shí)間，這里介紹一個(gè)比較好用的字符串截取函數(shù)，能夠勝任基本的需求了。

1. 截取GB2312中文字符串

復(fù)制代碼代碼如下:

 
< ?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; 
} 
?> 

2. 截取utf8編碼的多字節(jié)字符串

復(fù)制代碼代碼如下:

 
< ?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); 
} 
?> 

3. UTF-8、GB2312都支持的漢字截取函數(shù)

復(fù)制代碼代碼如下:

 
< ?php 
/* 
Utf-8、gb2312都支持的漢字截取函數(shù) 
cut_str(字符串, 截取長(zhǎng)度, 開(kāi)始長(zhǎng)度, 編碼); 
編碼默認(rèn)為 utf-8 
開(kāi)始長(zhǎng)度默認(rèn)為 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'); 
?> 

4. BugFree 的字符截取函數(shù)

復(fù)制代碼代碼如下:

 
< ?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 <wwccss@263.net> 
* @param string $String the string to cut. 
* @param int $Length the length of returned string. 
* @param booble $Append whether append "...": false|true 
* @return string the cutted string. 
*/ 
function sysSubStr($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 = "17test.info 走在中國(guó)自動(dòng)化測(cè)試的前沿"; 
$Length = "18"; 
$Append = false; 
echo sysSubStr($String,$Length,$Append); 
?> 