一个ubbcode的函数，速度很快.

前面见到有人发表
但是速度比较慢，也非常长
这里给出一种

functionubb($str){  
$color=Array("red","blue","green");
$str=eregi_replace("\[url\]([a-zA-Z0-9@:%_.~#-\?&]+)\[\/url\]","<ahref=http://\\1>\\1</a>",$str);//url
$str=eregi_replace("\[url=http://([a-zA-Z0-9@:%_.~#-\?&]+)\](.+)\[\/url\]","<ahref=\\1target=_blank>\\2</a>",$str);
$str=eregi_replace("\[url=([a-zA-Z0-9@:%_.~#-\?&]+)\](.+)\[\/url\]","<ahref=http://\\1target=_blank>\\2</a>",$str);
$str=eregi_replace("\[img\]([a-zA-Z0-9@:%_.~#-\?&]+)\[\/img\]","<imgsrc=http://\\1>\\1</img>",$str);//img
$str=eregi_replace("\[h([1-6])\](.+)\[\/h[1-6]\]","<h\\1>\\2</h\\1>",$str);//h1-6
$str=eregi_replace("\[email\]([_\.0-9a-z-]+@([0-9a-z][0-9a-z-]+\.)+[a-z]{2,3})\[\/email\]","<ahref=mailto:\\1>\\1</a>",$str);//email
$str=eregi_replace("\[email=([_\.0-9a-z-]+@([0-9a-z][0-9a-z-]+\.)+[a-z]{2,3})\](.+)\[\/email\]","<ahref=mailto:\\1>\\2</a>",$str);
$str=eregi_replace("\[b\](.+)\[\/b\]","<b>\\1</b>",$str);
$str=eregi_replace("\[i\](.+)\[\/i\]","<i>\\1</i>",$str);
$str=eregi_replace("\[size=(.+)\](.+)\[\/size\]","<fontsize=\\1>\\2</font>",$str);
$str=eregi_replace("\[color=(.+)\](.+)\[\/color\]","<fontcolor=\\1>\\2</font>",$str);
$str=eregi_replace("\[sub\](.+)\[\/sub\]","<sub>\\1</sup>",$str);//下裱
$str=eregi_replace("\[sup\](.+)\[\/sup\]","^\\1",$str);//上标
for($i=0;$i<=count($color);$i++)$str=eregi_replace("\[".$color[$i]."\](.+)\[\/".$color[$i]."\]","<fontcolor=".$color[$i].">\\1</font>",$str);
$str=preg_replace("/\[quote\](.+?)\[\/quote\]/is","<blockquote><fontsize="1"face="CourierNew">quote:</font><hr>\\1<hr></blockquote>",$str);
$str=preg_replace("/\[code\](.+?)\[\/code\]/is","<blockquote><fontsize="1"face="TimesNewRoman">code:</font><hrcolor="lightblue"><i>\\1</i><hrcolor="lightblue"></blockquote>",$str);
$str=preg_replace("/\[sig\](.+?)\[\/sig\]/is","<divstyle="text-align:left;color:darkgreen;margin-left:5%"><br><br>--------------------------<br>\\1<br>--------------------------</div>",$str);
return$str;
}