a = 5
print '%02d' % a
# output: 05
The '%' operator is called string formatting operator when used with a string on the left side. '%d'
is the formatting code to print out an integer number (you will get a type error if the value isn't numeric). With '%2d
you can specify the length, and '%02d'
can be used to set the padding character to a 0 instead of the default space.