写了个获取最新评论的函数，用substr截取，后面总会莫名其妙地多个乱码，原来 ，substr() 函数只能正确截取单字节字符串，所以针对双字节或多字节编码的字符就得自己动手了～···

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;
	}
}

更多的在这里：http://www.codebit.cn/pub/html/php_mysql/tip/data/substr/