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Variables and Data Types

Primitive data types

Python includes many primitive data types like many other languages.

  • String
    • str
  • Number types
    • int
    • float
    • complex
  • Boolean types
    • bool

Notice that there is no char data type to represent a character-type.

Assigning variables

Code sample link: https://replit.com/@jjoco/python-vars

Like in all other programming languages, data types can be assigned to variables. Since Python is not statically typed, there is no need to type a variable before running Python code. Consider the following: 

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countNoType = 5
If a variable is assigned to a literal, the interpreter will figure out the type of the variable based on the literal used, an integer in this case.

Type hinting

Starting from Python 3.5, developers can hint to the data type used for a variable, like so: 

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countWithType: int = 3
However, this is not exactly the same as static typing; Python3 will not enforce that the literal assigned to a variable will be the same as the type hint. For example, a valid statement that can run with no Python interpreter errors can be 
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countWithType: int = "hello"

Operators

Code sample link: https://replit.com/@jjoco/python-operators

In Python, there are different operators between two operands: arithmetic, logical, and assignment.

Arithmetic

Python supports arithmetic between two variables:

  • Addition: + : x + y --> (5 + 2) == 7
  • Subtraction: -: x - y --> (5 - 2) == 3
  • Multiplication: *: x * y --> (5 * 2) == 10
  • Division: /: x / y --> (5 / 2) == 2.5
  • Floor (Integer) Division //: x // y --> (5 // 2) == 2
  • Modulo (Remainder) %: x % y --> (5 % 2) == 1
  • Exponent **: x**y --> (5 ** 3) == 125

Logical

Comparison operators between two operands are supported

  • Less than <: x < y --> (5 < 2) == False
  • Less than or equal to <=: x <= y --> (5 <= 2) == False
  • Equal to ==: x == y --> (5 == 2) == False
  • Greater than or equal to >=: x >= y --> (5 >= 2) == True
  • Greater than >: x > y --> (5 > 2) == True
  • Not equal !=: x != y --> (5 != 2) == True

Arithmetic assignment operators

Assigning a variable the result of an arithmetic operation between the variable's previous value and another operand is supported.

  • Add, then assign: +=: x += y
  • Subtract, then assign -=: x -= y
  • Multiply, then assign *=: x *= y
  • Divide, then assign /=: x /= y
  • Modulo, then assign: %=: x %= y

Unlike other languages, Python does not support the increment (ie ++) or decrement (--) operators. You need to use +=1 or -=1 on the accumulator.

Bitwise

Operations between numbers on a bit-level are supported.

  • Bitwise AND &
  • Bitwise OR |
  • Bitwise XOR ^
  • Bitwise NOT ~
  • Bitwise left shift <<
  • Bitwise right shift >>