php string operation

I have stucked into a typical php string program. I have a data string like

$str="{heading}
{youtube}4vfOPm6wfyI{/youtube}
{/heading}
<p>Sed ut perspiciatis unde omnis iste n开发者_StackOverflow中文版atus error sit voluptatem accusantium doloremque laudantium</p>";

now i want the 4vfOPm6wfyI , the id of the link. How it will be done?

Thanks

Use explode to find the key. This will extract the key for you:

$arr = explode("{youtube}", $str);
$arr = explode("{/youtube}", $arr[1]);
$key = $arr[0];
print $key;

Just do a regular expression search/replace of \{youtube\}(.*?)\{\/youtube\} with the proper embed line:

<object width="640" height="385">
  <param name="movie" value="http://www.youtube.com/v/$1"></param>
  <param name="allowFullScreen" value="true"></param>
  <param name="allowscriptaccess" value="always"></param>
  <embed src="http://www.youtube.com/v/$1" 
    type="application/x-shockwave-flash" 
    allowscriptaccess="always" 
    allowfullscreen="true" 
    width="640" 
    height="385"></embed>
</object>

EDIT: If you just want to capture what's in between the {youtube} and {/youtube}, do something like this:

if (ereg ("\{youtube\}(.*?)\{\/youtube\}", $str, $regs)) {
  print "<p>The youtube link is: http://www.youtube.com/v/$regs[1]</p>";
}