What is the easiest way to parse a string and replace 1/2 with ½ (and similar) in PHP?

Question

I have a string with many fractions like 1/2, 1/4 etc. I want to replace them with their Unicode equivalents.

I realise I could pick them up with

/\s(\d+)\/(\d+)\s/

How would I replace them with their Unicode equivalents? I could probably wrap the numbers in span and do something similar with CSS, but I was wondering if there was an easy way to convert them.

Do I need to have a 1:1 mapping of regex to Unicode character?

Thanks

Answer 1

Given that there's only a few of them, you could just create a mapping like so:

$fractions = array(
    '1/4' => '¼', '1/3' => '⅓',
    '3/8' => '⅜', ...
  );

I'd say that's probably the easiest way... kind in mind that many people won't have fonts installed that can display all of them anyway.

Answer 2

You'll have better luck displaying it this way. Not everyone may have those Unicode fonts you need.

echo preg_replace ( '/\b(\d+)\/(\d+)\b/', '<sup>$1</sup>/<sub>$2</sub>', $fraction );

or:

echo preg_replace ( '/\b(\d+)\/(\d+)\b/', '<sup>$1</sup>&#8260;<sub>$2</sub>', $fraction );

The fractional slash ⁄ will look like ⁄.

This is still the best solution if you need to display large fractions: ²⁵⁶⁷⁄₅₇₉₈