Basic Data Types

Strings

Single quote

Example using single quotes:

    >>> string_1 = 'using single quotes'
    >>> string_2 = 'using single (')'
      File "<stdin>", line 1
       string_2 = 'using single (')'
                                  ^
    SyntaxError: unmatched ')'
    >>> string_2 = 'using single (\')'

Double quotes

Example using double quotes:

    >>> string_3 = "using double quotes"
    >>> string_4 = "using " quotes"
        File "<stdin>", line 1
        string_4 = "using " quotes"
                                  ^ SyntaxError: unterminated string literal (detected at line 1)
    >>> string_4 = "using \" quotes"

Triple quotation

Example using triple quotes:

    >>> string_5 = '''using triple single quotes'''
    >>> string_6 = '''using triple ' '''
    >>> string_7 = """using triple double quotes"""
    >>> string_7 = """using triple " """
    >>> string_8 = """using
    ... a
    ... multiline
    ... string
    ... handling '
    ... and ""
    ... """

String Formatting

3 ways to perform string formatting:

Using the modulo % character.
Using the .format() string method.
New method since Python 3.6: f-strings.

See:

Numeric

Python 2: int, long, float, complex
Python 3: int, float, complex

Integers

In Python 2 an int may be promoted to a long in Python 3 stays as int:

    >>> n = 11
    >>> type(n)
    <type 'int'>
    >>> n
    11
    >>> print(n)
    11

Python 2:

    >>> import sys
    >>> sys.maxint
    2147483647

Python 3:

    >>> sys.maxint
    Traceback (most recent call last):
    File "<stdin>", line 1, in <module> AttributeError: module 'sys' has no
    attribute 'maxint'

Python 2:

    >>> n = 2147483647
    >>> n = n + 1
    >>> type(n)
    <type 'long'>
    >>> n
    2147483648L
    >>> print(n)
    2147483648
    >>> n = - sys.maxint - 1
    -2147483648
    >>> type(n)
    <type 'int'>

Python 3:

    >>> n = 1
    >>> n
    1
    >>> type(n)
    <class 'int'>
    >>>

Floats

Python 2:

    >>> f = 5.2
    >>> type(f)
    <type 'float'>
    >>> print(f)
    5.2

Python 3:

    >>> f = 5.2
    >>> type(f)
    <type 'float'>
    >>> print(f)
    5.2

Python 2:

    >>> f = 5/2
    >>> type(f)
    <type 'int'>
    >>> f
    2

Python 3:

    >>> f = 5/2
    >>> type(f)
    <class 'float'>
    >>> f
    2.5

Complex

    >>> z = 3 + 5.7j
    >>> type(z)
    <type 'complex'>
    >>> z.real
    3.0
    >>> z.imag 5.7

Boolean

    True, False

    >>> type(True)
    <type 'bool'>

    >>> a = 1
    >>> b = 2
    >>> a == b
    False
    >>> a != b
    True

    >>> bool(0)
    False
    >>> bool(123)
    True
    >>> bool("")
    False
    >>> int(True)
    1
    >>> 5 + True
    6

Python 2: note that True or False were not a keyword so it was possible to re-assign:

    >>> True
    True
    >>> False
    False
    >>> True=False
    >>> True
    False

Python 3: expected behaviour

    >>> True=False
    File "<stdin>", line 1
    SyntaxError: can't assign to keyword