Preg replace help

What do u get if 1/2 + 1/3?

How do i use preg replace to select the fractions part? I need to add html <strong> to bold only the fractions part. Is there regex involved?

I tried this

<?php
$string = 'what do u get 1/2?';
$pattern = '/(\d+) (/) (\d+)/i';
$replacement = '$1 | $3';
echo preg_replace($pattern, $replacement, $string);
?>

but i didn't work...

Nothing came out

Enable error reporting by setting the following directives in your php.ini file. Then restart Apache and see what errors you get.

error_reporting = -1

display_errors = On

<style type="text/css">
span.highlight {font-weight:bold;} 
</style>

<?php
$string = 'what do u get 1/2?';
$pattern = '/([0-9][\/][0-9])/';
echo preg_replace($pattern, '<span class="highlight">\1</span>', $string);
?>

@shamuraq

a) the most immediate reason your preg_replace didn't work was because you have spaces between the part of your pattern that match for the numbers vs. the /, so it expects for instance "1 / 2"  not "1/2". 

b) supposing your string does have a fraction with spaces in it like "1 / 2" your replacement basically just swaps out the "/" for a "|"...which..why? You said you wanted to mark it up with some html strong...

@QuickOldCar: couple things about your regex..

a) since you are matching for a / it would be cleaner to pick a different pattern delimiter so you don't have to escape it in the pattern.

b)  [..] is a character class. It means to match any one thing inside the bracket. It is good for if you want to match for more than 1 thing like something in a range.  For example [a-z0-9] will match any 1 letter or number.  Since you are only matching for one thing (a "/"), while it *technically* works, there's no need for a character class.

c) Your pattern will only match single-digit fractions.  For instance, it will not match 1/10 (it will only match 1/1 part of it).

@shamuraq:

Here is a pattern for you:

$pattern = '~([0-9]+\s?+/\s?[0-9]+)~';

This will capture the entire fraction  $1 or \1 for your $replacement variable.  This pattern will allow for both "1/2" and "1 / 2".  If you only want it to match if no spaces, remove the two "\s?" parts.

thanx .josh. Really appreciate it...