11.5. Operator String Operators

  • + - add

  • - - sub

  • * - mul

  • % - mod

  • += - iadd

  • -= - isub

  • *= - imul

  • %= - imod

11.5.1. About

Table 11.1. String Operator Overload

Operator

Method

obj + other

obj.__add__(other)

obj - other

obj.__sub__(other)

obj * other

obj.__mul__(other)

obj % other

obj.__mod__(other)

obj += other

obj.__iadd__(other)

obj -= other

obj.__isub__(other)

obj *= other

obj.__imul__(other)

obj %= other

obj.__imod__(other)

11.5.2. Mod

  • % (__mod__) operator behavior for int and str:

>>> 13 % 4
1
>>>
>>> '13' % '4'
Traceback (most recent call last):
TypeError: not all arguments converted during string formatting
>>> pi = 3.1514
>>>
>>>
>>> 'String: %s' % pi
'String: 3.1514'
>>>
>>> 'Double: %d' % pi
'Double: 3'
>>>
>>> 'Float: %f' % pi
'Float: 3.151400'
>>> firstname = 'Mark'
>>> lastname = 'Watney'
>>>
>>>
>>> 'Hello %s' % firstname
'Hello Mark'
>>>
>>> 'Hello %s %s' % (firstname, lastname)
'Hello Mark Watney'
>>>
>>> 'Hello %(fname)s %(lname)s' % {'fname': firstname, 'lname': lastname}
'Hello Mark Watney'
>>> text = 'Hello %s'
>>> text %= 'Mark Watney'
>>>
>>> print(text)
Hello Mark Watney
>>> class Str:
...     def __mod__(self, other):
...         """str substitute"""
...
...         if type(other) is str:
...             ...
...         if type(other) is tuple:
...             ...
...         if type(other) is dict:
...             ...

Note, that using %s, %d, %f is currently deprecated in favor of f'...' string formatting. More information in Builtin Printing