How to add leading zeroes to format?

Question

I need a print function that writes Loop i / round, where both values i and round have to have at least four digits (12 -> 0012). It must have the format-method too.

I found the paste formatC and other ways to add leading zeroes but I can't make them work for this case..

It needs to be like this:

print('Loop {} / {}'.format('i', 'round'))

But with four digit numbers as I said.

Answer 1

number_str = str(a_number)
zero_filled_number = number_str.zfill(4)

a_number is 12. zero_filled_number will give you 0012

Answer 2

Use print("{:02d}".format(1)) as found in this answer.