String to int newbie question

[Boris Genz]

I have the following problem:
I want to convert a number string ( '3211' for example ) to a number, 
( actually integer ) preserving the original number ( the exact number being
string and integer ), but if my number string starts with one or more zeroes,
then the numbers won't be same...
For example, if I have string = '0027' then int(string) would give 27.
How can I add leading zeroes to that number?
I know it's a rather stupid question, but please help...