Operators

Operators are special symbols in Python that carry out arithmetic or logical computation. The value that the operator operates on is called the operand. For example:

>>> 2+3
5

Here, + is the operator that performs addition. 2 and 3 are the operands and 5 is the output of the operation. Python has a number of operators which are classified below.

Arithmetic operators

Arithmetic operators are used to perform mathematical operations like addition, subtraction, multiplication etc.

Here is an example.

x = 15
y = 4
print('x + y = ',x+y)
print('x - y = ',x-y)
print('x * y = ',x*y)
print('x / y = ',x/y)
print('x // y = ',x//y)
print('x ** y = ',x**y)

Output

x + y =  19
x - y =  11
x * y =  60
x / y =  3.75
x // y =  3
x ** y =  50625

Comparison operators

Comparison operators are used to compare values. It either returns True or False according to the condition.

Here is an example.

x = 10
y = 12
print('x > y  is',x>y)
print('x < y  is',x<y)
print('x == y is',x==y)
print('x != y is',x!=y)
print('x >= y is',x>=y)
print('x <= y is',x<=y)

Output

x > y  is False
x < y  is True
x == y is False
x != y is True
x >= y is False
x <= y is True

Logical operators

Logical operators are the and, or, not operators.

Here is an example.

x = True
y = False
print('x and y is',x and y)
print('x or y is',x or y)
print('not x is',not x)

Output

x and y is False
x or y is True
not x is False

Here is the truth table for these operators.

Bitwise operators

Bitwise operators act on operands as if they were string of binary digits. It operates bit by bit, hence the name. For example, 2 is 10 in binary and 7 is 111.

Let x = 10 (0000 1010 in binary) and y = 4 (0000 0100 in binary)

Assignment operators

Assignment operators are used in Python to assign values to variables. a = 5 is a simple assignment operator that assigns the value 5 on the right to the variable a on the left. There are various compound operators in Python like a += 5 that adds to the variable and later assigns the same. It is equivalent to a = a + 5.

Special operators

Python language offers some special type of operators like the identity operator or the membership operator. They are described below with examples.

Identity operators

is and is not are the identity operators in Python. They are used to check if two values (or variables) are located on the same part of the memory. Two variables that are equal does not imply that they are identical.

Here is an example.

x1 = 5
y1 = 5
x2 = 'Hello'
y2 = 'Hello'
x3 = [1,2,3]
y3 = [1,2,3]
print(x1 is not y1)
print(x2 is y2)
print(x3 is y3)

Output

False
True
False

Here, we see that x1 and y1 are integers of same values, so they are equal as well as identical. Same is the case with x2 and y2 (strings). But x3 and y3 are list. They are equal but not identical. Since list are mutable (can be changed), interpreter locates them separately in memory although they are equal.

Membership operators

in and not in are the membership operators in Python. They are used to test whether a value or variable is found in a sequence (string, list, tuple, set and dictionary). In a dictionary we can only test for presence of key, not the value.

Here is an example.

x = 'Hello world'
y = {1:'a',2:'b'}
print('H' in x)
print('hello' not in x)
print(1 in y)
print('a' in y)

Output

True
True
True
False

Here, 'H' is in x but 'hello' is not present in x (remember, Python is case sensitive). Similary, 1 is key and 'a' is the value in dictionary y. Hence, 'a' in y returns False.