根据中文裁减字符串函数的php代码

define(CHARSET, 'UTF-8'); // 系统默认编码 /** 
* 根据中文裁减字符串 
* @param $string - 字符串 
* @param $length - 长度 
* @param $doc - 缩略后缀 
* @return 返回带省略号被裁减好的字符串 
*/ 
function cutstr( $string, $length, $dot = '...' ) { 
if ( strlen( $string ) <= $length ) { 
return $string; 
} 
$pre = chr( 1 ); 
$end = chr( 1 ); 
$string = str_replace( array( '&', '"', '<', '>' ), array( $pre . '&' . $end, $pre . '"' . $end, $pre . '<' . $end, $pre . '>' . $end ), $string ); 
$strcut = ''; 
if ( strtolower( CHARSET ) == 'utf-8' ) { 
$n = $tn = $noc = 0; 
while ( $n < strlen( $string ) ) { 
$t = ord( $string[$n] ); 
if ( $t == 9 || $t == 10 || (32 <= $t && $t <= 126) ) { 
$tn = 1; 
$n++; 
$noc++; 
} elseif ( 194 <= $t && $t <= 223 ) { 
$tn = 2; 
$n += 2; 
$noc += 2; 
} elseif ( 224 <= $t && $t <= 239 ) { 
$tn = 3; 
$n += 3; 
$noc += 2; 
} elseif ( 240 <= $t && $t <= 247 ) { 
$tn = 4; 
$n += 4; 
$noc += 2; 
} elseif ( 248 <= $t && $t <= 251 ) { 
$tn = 5; 
$n += 5; 
$noc += 2; 
} elseif ( $t == 252 || $t == 253 ) { 
$tn = 6; 
$n += 6; 
$noc += 2; 
} else { 
$n++; 
} 
if ( $noc >= $length ) { 
break; 
} 
} 
if ( $noc > $length ) { 
$n -= $tn; 
} 
$strcut = substr( $string, 0, $n ); 
} else { 
for ( $i = 0; $i < $length; $i++ ) { 
$strcut .= ord( $string[$i] ) > 127 ? $string[$i] . $string[++$i] : $string[$i]; 
} 
} 
$strcut = str_replace( array( $pre . '&' . $end, $pre . '"' . $end, $pre . '<' . $end, $pre . '>' . $end ), array( '&', '"', '<', '>' ), $strcut ); 
$pos = strrpos( $strcut, chr( 1 ) ); 
if ( $pos !== false ) { 
$strcut = substr( $strcut, 0, $pos ); 
} 
return $strcut . $dot; 
}