Detect HTML tags in a string

I need to detect whether a string contains HTML tags.

if(!preg_match('(?<=<)\w+(?=[^<]*?>)', $string)){ 
    return $string;
}

The above regex gives me an error:

preg_match() [function.preg-match]: Unknown modifier '\'

I'm not well up on regex so not sure what the problem was. I tried escaping the \ and it didn't do anything.

Is there a better solution than regex? If not, what would be the correct regex to work with the preg_match?

Solution 1:

A simple solution is:

if($string != strip_tags($string)) {
    // contains HTML
}

The benefit of this over a regex is it's easier to understand, however I could not comment on the speed of execution of either solution.

you need to 'delimit' the regex with some character or another. Try this:

if(!preg_match('#(?<=<)\w+(?=[^<]*?>)#', $string)){ 
    return $string;
}