PHP RegEx question

[Greebo]

Given a string in the format:
a:3:{s:3:"usd";s:5:"12.00";s:3:"gbp";s:4:"0.00";s: 3:"eur";s:4:"0.00";}

(That's the cost field from the subscription table)

What would the best technique be to get at the string value bewteen the 3rd and 4th " and convert it to a float?

[Marco van Herwaarden]

PHP Code:

$myarray = unserialize($string); 

Then reference the $myarray['2'] variable.