很久没来这里了，各位可好？！

<?
//ubbcode类
  class ubbcode{
  var $call_time=0;
  //可处理标签及处理函数对应表
  var $tags = array( //小写的标签 => 对应的处理函数
  'url' => '$this->url',
  'email' => '$this->email',
  'img' => '$this->img',
'flash' => '$this->flash',
'sound' => '$this->sound',

'black' => '$this->font_color',
'white' => '$this->font_color',
'red' => '$this->font_color',
'pink' => '$this->font_color',
'blue' => '$this->font_color',
'green' => '$this->font_color',
'olive' => '$this->font_color',
'navy' => '$this->font_color',
'gray'=> '$this->font_color',
'fuchsia' => '$this->font_color',
'yellow' => '$this->font_color',
'silver' => '$this->font_color',
'purple' => '$this->font_color',

'marquee' => '$this->simple',
  'b' => '$this->simple',
  'i' => '$this->simple',
  'u' => '$this->simple',
  'tt' => '$this->simple',
  's' => '$this->simple',
  'strike' => '$this->simple',
  'h1' => '$this->simple',
  'h2' => '$this->simple',
  'h3' => '$this->simple',
  'h4' => '$this->simple',
  'h5' => '$this->simple',
  'h6' => '$this->simple',
  'sup' => '$this->simple',
  'sub' => '$this->simple',
  'em' => '$this->simple',
  'strong' => '$this->simple',
  'code' => '$this->simple',
  'samp' => '$this->simple',
  'kbd' => '$this->simple',
  'var' => '$this->simple',
  'dfn' => '$this->simple',
  'cite' => '$this->simple',
  'small' => '$this->simple',
  'big' => '$this->simple',
  'blink' => '$this->simple'
  );
  //url裢接属性
  var $attr_url;
  //url合法性检查对象
  var $urlcheck;
   
  function ubbcode($attr_url){
  $this->attr_url = ''.$attr_url;
  $this->urlcheck = new urlcheck();
  }
   
  //对$str进行UBB编码解析
  function parse($str){
  $this->call_time++;
  $parse = ''.htmlencode($str);
   
  $ret = '';
  while(true){
  $eregi_ret=eregi("\[[#]{0,1}[[:alnum:]]{1,7}\]",$parse,$eregi_arr); //查找[xx]
  if(!$eregi_ret){
  $ret .= $parse;
  break; //如果没有，返回
  }
  $pos = @strpos($parse,$eregi_arr[0]);
  $tag_len=strlen($eregi_arr[0])-2;//标记长度
  $tag_start=substr($eregi_arr[0],1,$tag_len);
  $tag=strtolower($tag_start);
   
  if((($tag=="url") or ($tag=="email") or ($tag=="img") or ($tag=="flash")) and ($this->call_time>1)){
  echo $this->call_time."<br>";
  return $parse;//如果不能是不能嵌套的标记，直接返回
  }
   
  $parse2 = substr($parse,0,$pos);//标记之前
  $parse = substr($parse,$pos+$tag_len+2);//标记之后
  if(!isset($this->tags[$tag])){
  echo "$tag_start<br>";
  $ret .= $parse2.'['.$tag_start.']';
  continue;//如果是不支持的标记
  }
   
  //查找对对应的结束标记
  $eregi_ret=eregi("\[\/".$tag."\]",$parse,$eregi_arr);
  if(!$eregi_ret){
  $ret .= $parse2.'['.$tag_start.']';
  continue;//如果没有对应该的结束标记
  }
  $pos=strpos($parse,$eregi_arr[0]);
  $value=substr($parse,0,$pos);//这是起止标记之间的内容
  $tag_end=substr($parse,$pos+2,$tag_len);
  $parse=substr($parse,$pos+$tag_len+3);//结束标记之后的内容
   
  if(($tag!="url") and ($tag!="email") and ($tag!="img")and ($tag!="flash")){
  $value=$this->parse($value);
  }
   
  $ret .= $parse2;
  eval('$ret .= '.$this->tags[$tag].'("'.$tag_start.'","'.$tag_end.'","'.$value.'");');
  }
  $this->call_time--;
  return $ret;
  }
   
  function simple($start,$end,$value){
  return '<'.$start.'>'.$value.'</'.$end.'>';
  }
   
  function url($start,$end,$value){
  $trim_value=trim($value);
  if (strtolower(substr($trim_value,0,7))!="http://")
  $trim_value="http://".$trim_value;
  if($this->urlcheck->check($trim_value)) return '<a href="'.$trim_value.'" '.$this->attr_url.'>'.$value.'</a>';
  else return '['.$start.']'.$value.'[/'.$end.']';
  }
   
  function email($start,$end,$value){
  if(emailcheck($value)) return '<a href="mailto:'.$value.'">'.$value.'</a>';
  else return '['.$start.']'.$value.'[/'.$end.']';
  }
   
  function img($start,$end,$value){
  $trim_value=trim($value);
  if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))
  return '<img src="'.$trim_value.'"></img>';
  else return '['.$start.']'.$value.'[/'.$end.']';
  }

  function flash($start,$end,$value){
  $trim_value=trim($value);
  if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))

return '<embed src='.$trim_value.' quality=high pluginspage=http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash type=application/x-shockwave-flash width=520 height=360>';

  else return '['.$start.']'.$value.'[/'.$end.']';
  }

function sound($start,$end,$value){
  $trim_value=trim($value);
  if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))

return "<embed src=".$trim_value." hidden autostart=true loop=true>";

  else return '['.$start.']'.$value.'[/'.$end.']';
  }

function font_color($start,$end,$value){
if(strstr("black|white|red|pink|blue|green|olive|navy|gray|fuchsia|yellow|silver|purple",$start))
return "<font color=".$start.">".$value."</font>";
else return '['.$start.']'.$value.'[/'.$end.']';
  }
  }
   
//urlcheck.php
  class urlcheck{
  var $regex = array(//协议名(注意在这里必须写成小写) => 对应的正则表达式
  'ftp' => '$this->ftpurl',
  'file' => '$this->fileurl',
  'http' => '$this->httpurl',
  'https' => '$this->httpurl',
  'gopher' => '$this->gopherurl',
  'news' => '$this->newsurl',
  'nntp' => '$this->nntpurl',
  'telnet' => '$this->telneturl',
  'wais' => '$this->waisurl'
  );
   
  var $lowalpha;
  var $hialpha;
  var $alpha;
  var $digit;
  var $safe;
  var $extra;
  var $national;
  var $punctuation;
  var $reserved;
  var $hex;
  var $escape;
  var $unreserved;
  var $uchar;
  var $xchar;
  var $digits;
   
  var $urlpath;
  var $password;
  var $user;
  var $port;
  var $hostnumber;
  var $alphadigit;
  var $toplabel;
  var $domainlabel;
  var $hostname;
  var $host;
  var $hostport;
  var $login;
   
  //ftp
  var $ftptype;
  var $fsegment;
  var $fpath;
  var $ftpurl;
   
  //file
  var $fileurl;
   
  //http,https
  var $search;
  var $hsegment;
  var $hpath;
  var $httpurl;
   
  //gopher
  var $gopher_string;
  var $selector;
  var $gtype;
  var $gopherurl;
   
  //news
  var $article;
  var $group;
  var $grouppart;
  var $newsurl;
   
  //nntp
  var $nntpurl;
   
  //telnet
  var $telneturl;
   
  //wais
  var $wpath;
  var $wtype;
  var $database;
  var $waisdoc;
  var $waisindex;
  var $waisdatabase;
  var $waisurl;
   
  function check($url){
  $pos = @strpos($url,':',1);
  if($pos<1) return false;
  $prot = substr($url,0,$pos);
  if(!isset($this->regex[$prot])) return false;
  eval('$regex = '.$this->regex[$prot].';');
  return ereg('^'.$regex.'$',$url);
  }
   
  function urlcheck(){
  $this->lowalpha = '[a-z]';
  $this->hialpha = '[A-Z]';
  $this->alpha = '('.$this->lowalpha.'|'.$this->hialpha.')';
  $this->digit = '[0-9]';
  $this->safe = '[$.+_-]';
  $this->extra = '[*()\'!,]';
  $this->national = '([{}|\^~`]|\\[|\\])';
  $this->punctuation = '[<>#%"]';
  $this->reserved = '[?;/:@&=]';
  $this->hex = '('.$this->digit.'|[a-fA-F])';
  $this->escape = '(%'.$this->hex.'{2})';
  $this->unreserved = '('.$this->alpha.'|'.$this->digit.'|'.$this->safe.'|'.$this->extra.')';
  $this->uchar = '('.$this->unreserved.'|'.$this->escape.')';
  $this->xchar = '('.$this->unreserved.'|'.$this->reserved.'|'.$this->escape.')';
  $this->digits = '('.$this->digit.'+)';
   
  $this->urlpath = '('.$this->xchar.'*)';
  $this->password = '(('.$this->uchar.'|[?;&=]'.')*)';
  $this->user = '(('.$this->uchar.'|[?;&=]'.')*)';
  $this->port = $this->digits;
  $this->hostnumber = '('.$this->digits.'.'.$this->digits.'.'.$this->digits.'.'.$this->digits.')';
  $this->alphadigit = '('.$this->alpha.'|'.$this->digit.')';
  $this->toplabel = '('.$this->alpha.'|('.$this->alpha.'('.$this->alphadigit.'|-)*'.$this->alphadigit.'))';
  $this->domainlabel = '('.$this->alphadigit.'|('.$this->alphadigit.'('.$this->alphadigit.'|-)*'.$this->alphadigit.'))';
  $this->hostname = '(('.$this->domainlabel.'\\.)*'.$this->toplabel.')';
  $this->host = '('.$this->hostname.'|'.$this->hostnumber.')';
  $this->hostport = '('.$this->host.'(:'.$this->port.')?)';
  $this->login = '(('.$this->user.'(:'.$this->password.')?@)?'.$this->hostport.')';
   
  $this->ftptype = '[aidAID]';
  $this->fsegment = '(('.$this->uchar.'|[?:@&=])*)';
  $this->fpath = '('.$this->fsegment.'(/'.$this->fsegment.')*)';
  $this->ftpurl = '([fF][tT][pP]://'.$this->login.'(/'.$this->fpath.'(;[tT][yY][pP][eE]='.$this->ftptype.')?)?)';
   
  $this->fileurl = '([fF][iI][lL][eE]://('.$this->host.'|[lL][oO][cC][aA][lL][hH][oO][sS][tT])?/'.$this->fpath.')';
   
  $this->search = '(('.$this->uchar.'|[;:@&=])*)';
  $this->hsegment = '(('.$this->uchar.'|[;:@&=])*)';
  $this->hpath = '('.$this->hsegment.'(/'.$this->hsegment.')*)';
  $this->httpurl = '([hH][tT][tT][pP][sS]?://'.$this->hostport.'(/'.$this->hpath.'([?]'.$this->search.')?)?)';
   
  $this->gopher_string = '('.$this->xchar.'*)';
  $this->selector = '('.$this->xchar.'*)';
  $this->gtype = $this->xchar;
  $this->gopherurl = '([gG][oO][pP][hH][eE][rR]://'.$this->hostport.'(/('.$this->gtype.'('.$this->selector.'(%09'.$this->search.'(%09'.$this->gopher_string.')?)?)?)?)?)';
   
  $this->article = '(('.$this->uchar.'|[;/?:&=])+@'.$this->host.')';
  $this->group = '('.$this->alpha.'('.$this->alpha.'|'.$this->digit.'|[-.+_])*)';
  $this->grouppart = '([*]|'.$this->group.'|'.$this->article.')';
  $this->newsurl = '([nN][eE][wW][sS]:'.$this->grouppart.')';
   
  $this->nntpurl = '([nN][nN][tT][pP]://'.$this->hostport.'/'.$this->group.'(/'.$this->digits.')?)';
   
  $this->telneturl = '([tT][eE][lL][nN][eE][tT]://'.$this->login.'/?)';
   
  $this->wpath = '('.$this->uchar.'*)';
  $this->wtype = '('.$this->uchar.'*)';
  $this->database = '('.$this->uchar.'*)';
  $this->waisdoc = '([wW][aA][iI][sS]://'.$this->hostport.'/'.$this->database.'/'.$this->wtype.'/'.$this->wpath.')';
  $this->waisindex = '([wW][aA][iI][sS]://'.$this->hostport.'/'.$this->database.'[?]'.$this->search.')';
  $this->waisdatabase = '([wW][aA][iI][sS]://'.$this->hostport.'/'.$this->database.')';
  $this->waisurl = '('.$this->waisdatabase.'|'.$this->waisindex.'|'.$this->waisdoc.')';
  }
  }
   

function htmlencode($str){
  $str = (string)$str;
   
  $ret = '';
  $len = strlen($str);
  $nl = false;
  for($i=0;$i<$len;$i++){
  $chr = $str[$i];
  switch($chr){
  case '<':
  $ret .= '<';
  $nl = false;
  break;
  case '>':
  $ret .= '>';
  $nl = false;
  break;
  case '"':
  $ret .= '"';
  $nl = false;
  break;
  case '&':
  $ret .= '&';
  $nl = false;
  break;
  /*
  case ' ':
  $ret .= ' ';
  $nl = false;
  break;
  */
  case chr(9):
  $ret .= '    ';
  $nl = false;
  break;
/*
  case chr(10):
  if($nl) $nl = false;
  else{
  $ret .= '<br>';
  $nl = true;
  }
  break;

  case chr(13):
  if($nl) $nl = false;
  else{
  $ret .= '<br>';
  $nl = true;
  }
  break;
*/
  default:
  $ret .= $chr;
  $nl = false;
  break;
  }
  }
   
  return $ret;
  }
   
   
  function htmlencode4textarea($str){
  $str = (string)$str;
   
  $ret = '';
  $len = strlen($str);
  for($i=0;$i<$len;$i++){
  $chr = $str[$i];
  switch($chr){
  case '<':
  $ret .= '<';
  break;
  case '>':
  $ret .= '>';
  break;
  case '"':
  $ret .= '"';
  break;
  case '&':
  $ret .= '&';
  break;
  case ' ':
  $ret .= ' ';
  break;
  case chr(9):
  $ret .= '    ';
  break;
  default:
  $ret .= $chr;
  break;
  }
  }
   
  return $ret;
  }
   
  function emailcheck($email){
  $ret=false;
  if(strstr($email, '@') && strstr($email, '.')){
  if(eregi("^([_a-z0-9]+([\\._a-z0-9-]+)*)@([a-z0-9]{2,}(\\.[a-z0-9-]{2,})*\\.[a-z]{2,3})$", $email)){
  $ret=true;
  }
  }
  return $ret;
  }
   
  function str2url($path){
  return eregi_replace("%2f","/",urlencode($path));
  }

?>
--------------------------

说明：在网上找了半天发现全是何志强的那段代码，我也就拿来改了一下用上了。其中加入了一部分自己的内容，只是还不太清楚如何规定图片等元素的大小。我曾经把 function img($start,$end,$value){
  $trim_value=trim($value);
  if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))
  return '<img src="'.$trim_value.'"></img>';
  else return '['.$start.']'.$value.'[/'.$end.']';
  }
改为：
function img($start,$end,$value){
  $trim_value=trim($value);
  if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))
{
$pisces=explode(" ",$start);
if(!is_int($pisces[1]) || !!is_int($pisces[2]))
return '<img src="'.$trim_value.'" width=$pisces[1] height=$pisces[2]></img>';
else
return '<img src="'.$trim_value.'"></img>';
}
  
  else return '['.$start.']'.$value.'[/'.$end.']';
  }

但由于对前面的正则表达式不熟悉没成功。