preg_match must end with "/"?

In the preg_match below, I'm comparing against two static strings, $url and $my_folder...

  $url = get_bloginfo('url')
//$url = 'http://site.com'

  $my_folder = get_option('my_folder');
//$my_folder = 'http://site.com/somefolder;

I'm getting a match when the $my_folder string has a trailing slash

 http://somefolder/go/

But this does not create a match...

 http://somefolder/go

However, another problem is that this also matches...

 http://somefolder/gone

Code is...

$my_folder =  get_option('rseo_nofollow_folder');
if($my_folder !=='') $my_folder = trim($my_folder,'/');
$url = trim(get_bloginfo('url'),'/');

preg_match_all('~<a.*>~isU',$content["post_content"],$matches);

for ( $i = 0; $i <= sizeof($matches[0]); $i++){
    if($my_folder !=='')
    {
    //HERES WHERE IM HAVING PROBLEMS

        if ( !preg_match( '~nofollow~is',$matches[0][$i]) 
            && (preg_match('~' . $my_folder . '/?$~', $matches[0][$i]) 
            || !preg_match( '~'. $url .'/?$~',$matches[0][$i])))
        {
            $result = trim($matches[0][$i],">");
            $result .= ' rel="nofollow">';
            $content["post_content"] = str_replace($matches[0][$i], $result, $content["post_content"]);
        }
    }
    else
    {
    //THIS WORKS FINE, NO PROBLEMS HERE
        if ( !preg_match( '~nofollow~is',$matches[0][$i]) && (!preg_match( '~'.$url.'~',$matches[0][$i]))) 
            {
            开发者_开发知识库$result = trim($matches[0][$i],">");
            $result .= ' rel="nofollow">';
            $content["post_content"] = str_replace($matches[0][$i], $result, $content["post_content"]);
            }
    }
}
return $content;

~^http://somefolder/go(?:/|$)~

You need to first remove the trailing slash and add '/?' at the end of your regexp

$my_folder = trim($my_folder,'/');
$url = trim(get_bloginfo('url'),'/');

if ( !preg_match( '~nofollow~is',$matches[0][$i]) 
    && (preg_match('~' . $my_folder . '/?$~', $matches[0][$i]) 
    || !preg_match( '~'. $url .'/?$~',$matches[0][$i])))

This is a shot in the dark, but try:

preg_match( '/' . preg_quote( get_bloginfo('url'), '/' ) . '?/', $matches[0][$i] )

You can use whatever char you want in place of the / chars. I'm guessing that you're using wordpress and guessing that get_bloginfo('url') is normalized to always have a trailing slash. If that is the case, the last slash will be selected optionally by the ? at the end of the regex.

You should just use strstr() or strpos() if it's fixed strings anyway.

Your example rewritten:

if (!strstr($matches[0][$i], "nofollow") 
 and strstr($matches[0][$i], $my_folder) 
 or !strstr($matches[0][$i], $url)  )

strpos works similarly, but you need an extra boolean check:

if (strpos($matches, "nofollow") === FALSE
 or strpos($matches, $my_folder) !== FALSE)