Operators in Python

Operators in Python

Expressions in any programming language are a combination of operators and operands. Operators represent a computation and operands are the values or variables on which the computation is performed. When expressions are evaluated the result can be a numeric value or a Boolean value. The types of operators supported in Python are

1.    Arithmetic operators

2.    Assignment operators

3.    Relational operators

4.    Logical operators

5.    Membership operators

6.    Identity operators

Arithmetic operators:

Arithmetic operators are used for performing arithmetic operations. Various arithmetic operators are

Operator	Description	Example	Output
+	Addition	3 + 5	8
–	Subtraction	7 – 3	4
*	Multiplication	2 * 4	8
/	Division	9 / 3	3.0
%	Modulus (reminder operator)	5 % 2	1
//	Truncation (Floor) division	10 // 3 10 // 3.0 10.0 // 3	3 3.0 3.0
**	Exponentiation	2**3	8

Assignment operator

Assignment operator (=) is used to assign values to operands. The right side of the assignment operator may be a value or an expression. The output of the expression evaluation is assigned to the operand in the left side of the assignment operator. Example

a = 5                 (Direct assignment)

b = 3 + 4           (Evaluate expression containing values)

c = a * b           (Evaluate expression containing operands)

d = c + 1           (Evaluate expression containing values and operands)

Arithmetic Assignment operators are also called as shortcut operators. When an operator is used in the expression and the resultant value is assigned to the same operator it is called as arithmetic assignment operator. Example, consider

a += b                         is equal to                   a = a + b.

The value of a and b are added and the result is assigned to a. The old value of a is now replaced by the new value 8

           

Operator	Description	Example	Equivalent
+=	Addition assignment	a += b	a = a + b
–=	Subtraction assignment	a –= b	a = a – b
*=	Multiplication assignment	a *= b	a = a * b
/=	Division assignment	a /= b	a = a / b
%=	Modulus assignment	a %= b	a = a % b
//=	Truncation division assignment	a //= b	a = a // b
**=	Exponentiation assignment	a **= b	a = a ** b

Relational operators

Relational operators are also known as comparison operators and they return a Boolean value. They are used in conditional statements to compare values and take action depending on the result. If a = 5, b = 7 and c = 5

Operator	Description	Example	Result
==	Equal to	a == b	False
<	Less than	a < b	True
<=	Less than or Equal to	a <= b	True
>	Greater than	a > c	False
>=	Greater than or Equal to	a >= c	True
!=	Not equal to	a != b	True
<>	Similar to (!=)	a <> b	True

Logical operators

Logical operators are based on Boolean Algebra and they return a Boolean value. They are used in situations involving more than one conditional statement.

Operator	Description	Evaluation
and	AND	Returns True if ALL conditional statements returns True. Else returns False
or	OR	Returns True if atleast one of the conditional statements return True. Else returns False
not	Unary NOT	Returns True if the operand has zero value. Else returns False

Example if a = 5, b = 3 and c = 7

          ((a > b) and (a > c)) will return False

((a > b) or (a > c)) will return True

Membership operators

Membership operators checks whether an element is a member of a sequence or not. The sequence can be List, String, Tuple or Dictionary. Example If List1 = [2, 4, 6, 8]

Operator	Example	Result
in	2 in List1 3 in List1	True False
not in	2 not in List1 3 not in List1	False True

Identity operators

Identity operators are used to compare the memory locations of two Python objects. Returns true if the two variables on either side of is operator are referring to the same object. Else returns False. Example if

List1 = [2, 4, 6, 8]

List2 = List1

Operator	Example	Result
is	List1 is List2	True
is not	List1 is not List2	False

Order of operations (Operator precedence)

When more than one operator appears in the expression, the order of evaluation depends on the precedence of operators. For mathematical operators Python follows the PEMDAS rule

1.    Parenthesis has the highest precedence.

a.    Example (1+1)*5 = 10 and not 6

2.    Exponentiation has the next highest precedence

a.    Example 2**3+1 = 9 and not 16

3.    Multiplication and Division have higher precedence than Addition and Subtraction.

a.    Note: Multiplication and Division have equal precedence. Similarly Addition and Subtraction have the equal precedence.

b.    Example:

                                                 i.    2*6/4 = 3                             (equal precedence for * and /)

                                               ii.    2+4-3 = 3                             (equal precedence for + and -)

                                              iii.    2*6+4 = 16 and not 20          (higher precedence for * than +)

4.    When operators have equal precedence the expression is evaluated from left to right.