Python Operators

In this tutorial you will learn:

1. Arithmetic operators
2. Assignment operators
3. Comparison operators
4. Logical operators
5. Bitwise operators
6. Membership operators
7. Identity operators

Introduction:

Before we jump to the operators lets define what is an operator. An operator is a special symbol that python or any other programming language use to make some arithmetic, assignment or logical computation.

1 Arithmetic operators:

Arithmetic operators are used to perform mathematical operations that we are familliar with, like addition, subtraction, division and multiplication etc.

Lets see some examples:

 0#Addition
 1a = 4 + 5
 2print("a =", a)
 3
 4#Subtraction
 5b = 9 - 5
 6print("b =", b)
 7
 8#Division
 9c = 20 / 3
10print("c =", c)
11
12#Multiplication
13d = 2 * 4
14print("d =", d)
15
16#Floor division
17e = 20 // 3
18print("e =", e)
19
20#Modulus
21f = 10 % 2
22print("f =", f)
23
24#Exponent
25g = 5 ** 2
26print("g =", g)

OUTPUT: a = 9

OUTPUT: b = 4

OUTPUT: c = 6.66666666667

OUTPUT: d = 8

OUTPUT: e = 6

OUTPUT: f = 0

OUTPUT: g = 25

As you see this is how we can use these operators in python.
Lets take a look at the division operator, you see when we devide 20 by 3 (20 / 3) we get a floating point number : 6.66666666667, but when we use the Floor division operator we get an integer number: 6, this effect is the same when we use the int() built-in function to convert a float number.
Now lets look at the modulus operators: When we devide 10 by 2 the result will be 5 which mean there is zero remainder, and this is the job of the modulus it devides two numbers and return the remainder of the division.

2.Assignment operators:

We have already used an assignment operator which is the ‘=’ symbol.
We use the assignment operators to assign values to variables.

Lets see some code examples:

 0#Assign 5 to x
 1x = 5
 2
 3#Add 5 and assign
 4x += 8
 5print("x :", x)
 6
 7#Subtract and assign
 8x -= 2
 9print("x :", x)
10
11#Devide and assign
12x /= 2
13print("x :", x)
14
15#Multiply and assign
16x *= 5
17print("x :", x)
18
19#Modulus and assign
20x %= 2
21print("x :", x)
22
23#Exponent adn assign
24x **= 5
25print("x :", x)
26
27#Floor division and assign
28x //= 5
29print("x :", x)

OUTPUT: x : 13

OUTPUT: x : 11

OUTPUT: x : 5.5

OUTPUT: x : 27.5

OUTPUT: x : 1.5

OUTPUT: x : 7.59375

OUTPUT: x : 1.0

3 Comparison operators:

We use comparison operators to compare between values, the ruslt of the comparison will be a bool (True or False).

Lets see these operators in code:

 0#OUTPUT True
 1print(5 > 2)
 2
 3#OUTPUT False
 4print(5 > 10)
 5
 6#OUTPUT True
 7print(3 < 5)
 8
 9#OUTPUT False
10print(3 < 1)
11
12#OUTPUT True
13print(5 == 5)
14
15#OUTPUT False
16print(5 == 6)
17
18#OUTPUT True
19print(8 >= 8)
20
21#OUTPUT False
22print(8 >= 9)
23
24#OUTPUT True
25print(12 <= 15)
26
27#OUTPUT False
28print(12 <= 10)
29
30#OUTPUT True
31print(5 != 10)
32
33#OUTPUT False
34print(5 != 5)

4 Logical operators:

In python we have three logical operators “and”, “or”, “not”, these operators return a boolean result based on the condition.

Lest see some examples:

 0#OUTPUT True
 1x = (5 > 2 and 3 > 1)
 2print("x:", x)
 3
 4#OUTPUT True
 5y = (5 == 5 or 5 > 8)
 6print("y:", y)
 7
 8#OUTPUT False
 9z = (not 5 > 2)
10print("z:", z)

Lets take a look at this code:
In the first example we have assigned to “x” a logical operation, the first part is (5 > 2) this will return True, and the second part is (3 > 1) which also return True, and by using the logical “and” operator: True and True will return a True. If one of the comparison operator returned False, then the result of our logical operation will be False.
The second example is also devided in two part, the first is (5 == 5) which returns True and the second part is (5 > 8) which returns False, by using the “or” logical operator the result will be True, because the “or” operator needs one of the two operand to be True to return True.
The last example is very simple the comparison operation (5 > 2) return True, and by using the “not” operator we get the inverse of the result which is False in our case.

5 Bitwise operators:

Bitwise operators are used to perform a bit by bit operation.

Lets see some examples:

 0#x = 3 in binary
 1x = 0b00000011
 2
 3#y = 242 in binary
 4y = 0b11110010
 5
 6a = x & y
 7
 8'''
 9a = x & y
10
11Lets see how that happened
12
13x     = 00000011
14y     = 11110010
15-----------------
16x & y = 00000010
17'''
18
19#OUTPUT 2
20print(a)

As you see the “&” operator works like this: when it finds 1 1 it returns 1, if it finds 1 0 or 0 1 or 0 0 it returns 0.
To read more about bitwise operations click here

6 Membership operators:

Membership operators are used to check whether a value is in a sequence or not (like string, or list etc.)

0x = "Hello World"
1
2#OUTPUT True
3print('H' in x)
4
5#OUTPUT True
6print('h' not in x)

In the first example returns True because the uppercase ‘H’ is in the sequence, and the second example returns True because the lowecase ‘h’ is not in the sequence.
This mean that you need to be careful with this because it’s case sensitive, ‘h’ is different from ‘H’.

7 Identity operators:

Identity operators are used to check if two variables are located in the same memory location.

 0x = 5
 1y = 5.4
 2
 3#OUTPUT False
 4print(x is y)
 5
 6#OUTPUT True
 7print(x is not y)
 8
 9a = "hello world"
10b = "hello world"
11
12#OUTPUT False
13print(a is b)
14
15#OUTPUT True
16print(a is not b)

In this example we see that the variables “a” and “b” are both identical but when we check “a is b” we get False this mean that each one is located in a different location in memory. You can check the location of your variables using the id() built-in function:

0x = 5 
1
2#OUTPUT 49301269 THIS NUMBER WILL BE DIFFERENT ON YOUR MACHINE 
3print(id(x))

This is all for this tutorial, I hope you enjoyed it.