PHP 截取中文字符串方法总结
1. 截取GB2312中文字符串
< ?php <br />//截取中文字符串<br />function mysubstr($str, $start, $len) {<br /> $tmpstr = "";<br /> $strlen = $start + $len;<br /> for($i = 0; $i < $strlen; $i++) {<br /> if(ord(substr($str, $i, 1)) > 0xa0) {<br /> $tmpstr .= substr($str, $i, 2);<br /> $i++;<br /> } else<br /> $tmpstr .= substr($str, $i, 1);<br /> }<br /> return $tmpstr;<br />}<br />?>
2. 截取utf8编码的多字节字符串
< ?php<br />//截取utf8字符串<br />function utf8Substr($str, $from, $len)<br />{<br /> return preg_replace('#^(?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'.$from.'}'.<br /> '((?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'.$len.'}).*#s',<br /> '$1',$str);<br />}<br />?>
3. UTF-8、GB2312都支持的汉字截取函数
< ?php<br />/* <br />Utf-8、gb2312都支持的汉字截取函数 <br />cut_str(字符串, 截取长度, 开始长度, 编码); <br />编码默认为 utf-8 <br />开始长度默认为 0 <br />*/ <br /> <br />function cut_str($string, $sublen, $start = 0, $code = 'UTF-8') <br />{ <br /> if($code == 'UTF-8') <br /> { <br /> $pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/"; <br /> preg_match_all($pa, $string, $t_string); <br /> <br /> if(count($t_string[0]) - $start > $sublen) return join('', array_slice($t_string[0], $start, $sublen))."..."; <br /> return join('', array_slice($t_string[0], $start, $sublen)); <br /> } <br /> else <br /> { <br /> $start = $start*2; <br /> $sublen = $sublen*2; <br /> $strlen = strlen($string); <br /> $tmpstr = ''; <br /> <br /> for($i=0; $i< $strlen; $i++) <br /> { <br /> if($i>=$start && $i< ($start+$sublen)) <br /> { <br /> if(ord(substr($string, $i, 1))>129) <br /> { <br /> $tmpstr.= substr($string, $i, 2); <br /> } <br /> else <br /> { <br /> $tmpstr.= substr($string, $i, 1); <br /> } <br /> } <br /> if(ord(substr($string, $i, 1))>129) $i++; <br /> } <br /> if(strlen($tmpstr)< $strlen ) $tmpstr.= "..."; <br /> return $tmpstr; <br /> } <br />} <br /> <br />$str = "abcd需要截取的字符串"; <br />echo cut_str($str, 8, 0, 'gb2312'); <br />?>
4. BugFree 的字符截取函数
< ?php <br />/** <br /> * @package BugFree <br /> * @version $Id: FunctionsMain.inc.php,v 1.32 2005/09/24 11:38:37 wwccss Exp $ <br /> * <br /> * <br /> * Return part of a string(Enhance the function substr()) <br /> * <br /> * @author Chunsheng Wang <wwccss@263.net> <br /> * @param string $String the string to cut. <br /> * @param int $Length the length of returned string. <br /> * @param booble $Append whether append "...": false|true <br /> * @return string the cutted string. <br /> */ <br />function sysSubStr($String,$Length,$Append = false) <br />{ <br /> if (strlen($String) < = $Length ) <br /> { <br /> return $String; <br /> } <br /> else <br /> { <br /> $I = 0; <br /> while ($I < $Length) <br /> { <br /> $StringTMP = substr($String,$I,1); <br /> if ( ord($StringTMP) >=224 ) <br /> { <br /> $StringTMP = substr($String,$I,3); <br /> $I = $I + 3; <br /> } <br /> elseif( ord($StringTMP) >=192 ) <br /> { <br /> $StringTMP = substr($String,$I,2); <br /> $I = $I + 2; <br /> } <br /> else <br /> { <br /> $I = $I + 1; <br /> } <br /> $StringLast[] = $StringTMP; <br /> } <br /> $StringLast = implode("",$StringLast); <br /> if($Append) <br /> { <br /> $StringLast .= "..."; <br /> } <br /> return $StringLast; <br /> } <br />} <br /> <br />$String = "CodeBit.cn -- 简单、精彩、通用"; <br />$Length = "18"; <br />$Append = false; <br />echo sysSubStr($String,$Length,$Append); <br />?>

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Sessionlockingisatechniqueusedtoensureauser'ssessionremainsexclusivetooneuseratatime.Itiscrucialforpreventingdatacorruptionandsecuritybreachesinmulti-userapplications.Sessionlockingisimplementedusingserver-sidelockingmechanisms,suchasReentrantLockinJ

Alternatives to PHP sessions include Cookies, Token-based Authentication, Database-based Sessions, and Redis/Memcached. 1.Cookies manage sessions by storing data on the client, which is simple but low in security. 2.Token-based Authentication uses tokens to verify users, which is highly secure but requires additional logic. 3.Database-basedSessions stores data in the database, which has good scalability but may affect performance. 4. Redis/Memcached uses distributed cache to improve performance and scalability, but requires additional matching

Sessionhijacking refers to an attacker impersonating a user by obtaining the user's sessionID. Prevention methods include: 1) encrypting communication using HTTPS; 2) verifying the source of the sessionID; 3) using a secure sessionID generation algorithm; 4) regularly updating the sessionID.


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