Types

Calling type(foo) returns the actual class object of which foo is an instance (that is, not foo’s class’s name (a string), but rather the actual class object).

type(3)          # => int
type(3.1)        # => float
type('hi')       # => str
type([1, 2])     # => list
type((5, 7))     # => tuple
type({'a': 1})   # => dict
type({8, 9})     # => set

def f(x): pass
type(f)          # => function

type(max)        # => builtin_function_or_method

import sys
type(sys)        # => module

Note that although you usually capitalize the names of your own types/classes, by Python convention those built-in types above are all named lowercase.

Ints automatically widen to floats. To convert between other types, pass the object to the new type’s constructor.

3 + 1.0       # => 4.1 (a float)
3 + '1'       # throws TypeError
3 + int('1')  # => 4
str(3) + '1'  # => '31'