Question

In python, what does the 2nd % signifies?

print '%s' % ( i ) 

Answer 1

As others have said, this is the Python string formatting/interpolation operator. It’s basically the equivalent of sprintf in C, for example:

a = '%d bottles of %s on the wall' % (10, 'beer')

is equivalent to something like

a = sprintf('%d bottles of %s on the wall', 10, 'beer');

in C. Each of these has the result of a being set to '10 bottles of beer on the wall'

Note however that this syntax is deprecated in Python 3.0; its replacement looks something like

a = '{0} bottles of {1} on the wall'.format(10, 'beer')

This works because any string literal is automatically turned into a str object by Python.