TypeError: not all arguments converted during string formatting python

You’re mixing different format functions.

The old-style % formatting uses % codes for formatting:

'It will cost $%d dollars.' % 95

The new-style {} formatting uses {} codes and the .format method

'It will cost ${0} dollars.'.format(95)

Note that with old-style formatting, you have to specify multiple arguments using a tuple:

'%d days and %d nights' % (40, 40)

In your case, since you’re using {} format specifiers, use .format:

"'{0}' is longer than '{1}'".format(name1, name2)