Check text area to see if something exists

[Vivid Lust]

In php, how can i check a text area to see if something exists.

 

E.g. (in some made up coding!)

 

CHECK post('bott');

IF(lol !exist );{

print "please check your form";

}

 

Sorry for my no0bish example xD

 

Hope someone can help

 

Thanks in advanced!

[ignace]

$textarea = $_POST['textarea'];

 

$what = "foobar";

$init = substr($textarea, strpos($foobar));

if (empty($init)) {/* not in it */}