Replace one URL with another without regex - php

Question

I'm trying to replace some URLs in a database (wordpress) with another, but it's tricky because a lot of the URLs are redirects. I'm trying to either replace the URL with the redirected URL, or with a URL of my choosing, based on the result. I can get the matching done without any problems, but I can't replace it. I've tried str_replace, but it doesn't seem to replace the URLs. When I try preg_replace, it will give "Warning: preg_replace(): Delimiter must not be alphanumeric or backslash". Can anyone point me in the right way to do this?
if(preg_match($url_regex,$row['post_content'])){
preg_match_all($url_regex,$row['post_content'],$matches);
foreach($matches[0] as $match){
echo "{$row['ID']} \t{$row['post_date']} \t{$row['post_title']}\t{$row['guid']}";
$newUrl = NULL;
if(stripos($url_regex,'domain1') !== false || stripos($url_regex,'domain2') !== false || stripos($url_regex,'domain3') !== false){
$match = str_replace('&','&',$match);
$ch = curl_init();
curl_setopt($ch,CURLOPT_URL,$match);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
$html = curl_exec($ch);
$newUrl = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);
if(stripos($newUrl,'domain4') !== false)
$newUrl = NULL;
}
else
if($newUrl == NULL)
{ $newUrl = 'http://www.mysite.com/';
}
echo "\t$match\t$newUrl";
$content = str_replace($match,$newUrl,$row['post_content']);
echo "\t (" . strlen($content).")";
echo "\n";
}
}

Answer 1

This is how you would do it with Perl Regular Expressions.
$baesUrlMappings = array('/www.yoursite.com/i' => 'www.mysite.com',
'/www.yoursite2.com/i' => 'www.mysite2.com',);
echo preg_replace(array_keys($baesUrlMappings), array_values($baesUrlMappings), 'http://www.yoursite.com/foo/bar?id=123');
echo preg_replace(array_keys($baesUrlMappings), array_values($baesUrlMappings), 'http://www.yoursite2.com/foo/bar?id=123');
http://codepad.viper-7.com/2ne7u6
Please read the manual! You should be able to figure this out.