[SOLVED] HELP with preg_replace

[sastro]

here is my string

What is a regex<br>At its most basic level, a regex can be considered a method of pattern matching or matching patterns within a string.<br>In PHP the most oft used is PCRE or "Perl Compatible Regular Expressions".<br>Here we will try to decypher the meaningless hieroglyphics and set you on your way to a powerful tool for use in your applications.<br>Do not try to understand all this in a single sitting. Instead, take in a little and come back as you grasp various concepts. 

 

I need to replace the first "<br>" with "<br>blablabla<br>"... Only for the first "<br>". I try to put ads on "blablabla".

 

Thanks in advance...

[nrg_alpha]

Example:

$str = 'What is a regex<br>At its most basic level, a regex can be considered a method of pattern matching or matching patterns within a string.<br>In PHP the most oft used is PCRE or "Perl Compatible Regular Expressions".<br>Here we will try to decypher the meaningless hieroglyphics and set you on your way to a powerful tool for use in your applications.<br>Do not try to understand all this in a single sitting. Instead, take in a little and come back as you grasp various concepts.
';

$str = preg_replace('#<br>#i', '<br>blablabla<br>', $str, 1);
echo $str;

[sastro]

Works like a charm...

Thank you