OPERATORS

OPERATORS

Operators are used to perform operations on variables and values.

Python divides the operators in the following groups:

• Arithmetic operators

• Assignment operators

• Comparison operators

• Logical operators

• Identity operators

• Membership operators

• Bitwise operators

ARITHMETIC OPERATORS

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

There are 7 arithmetic operators in Python :

Addition

Subtraction

Multiplication

Division

Modulus

Exponentiation

Floor division

1. Addition Operator : In Python, + is the addition operator. It is used to add 2 values.

Example :

val1 = 2

val2 = 3

# using the addition operator

res = val1 + val2

print(res)

Output :

5

2. Subtraction Operator : In Python, – is the subtraction operator. It is used to subtract the second value from the first value.

Example :

val1 = 2

val2 = 3

# using the subtraction operator

res = val1 - val2

print(res)

Output :

-1

3. Multiplication Operator : In Python, * is the multiplication operator. It is used to find the product of 2 values.

Example :

val1 = 2

val2 = 3

# using the multiplication operator

res = val1 * val2

print(res)

Output :

6

4. Division Operator : In Python, / is the division operator. It is used to find the quotient when first operand is divided by the second.

Example :

val1 = 3

val2 = 2

# using the division operator

res = val1 / val2

print(res)

Output :

1.5

5. Modulus Operator : In Python, % is the modulus operator. It is used to find the remainder when first operand is divided by the second.

Example :

val1 = 3

val2 = 2

# using the modulus operator

res = val1 % val2

print(res)

Output :

1

6. Exponentiation Operator : In Python, ** is the exponentiation operator. It is used to raise the first operand to power of second.

Example :

val1 = 2

val2 = 3

# using the exponentiation operator

res = val1 ** val2

print(res)

Output :

8

7. Floor division : In Python, // is used to conduct the floor division. It is used to find the floorof the quotient when first operand is divided by the second.

Example :

val1 = 3

val2 = 2

# using the floor division

res = val1 // val2

print(res)

Output :

1

Assignment Operators

1) Assign: This operator is used to assign the value of the right side of the expression to the left side operand.

Syntax:

x = y + z

Example:

Python3

# Assigning values using

# Assignment Operator

a = 3

b = 5

c = a + b

# Output

print(c)

Output:

8

2) Add and Assign: This operator is used to add the right side operand with the left side operand and then assigning the result to the left operand.

Syntax:

x += y

Example:

Python3

a = 3

b = 5

# a = a + b

a += b

# Output

print(a)

Output:

8

3) Subtract and Assign: This operator is used to subtract the right operand from the left operand and then assigning the result to the left operand.

Syntax:

x -= y

Example –

Python3

a = 3

b = 5

# a = a - b

a -= b

# Output

print(a)

Output:

-2

4) Multiply and Assign: This operator is used to multiply the right operand with the left operand and then assigning the result to the left operand.

Syntax:

x *= y

Example:

Python3

a = 3

b = 5

# a = a * b

a *= b

# Output

print(a)

Output:

15

5) Divide and Assign: This operator is used to divide the left operand with the right operand and then assigning the result to the left operand.

Syntax:

x /= y

Example:

Python3

a = 3

b = 5

# a = a / b

a /= b

# Output

print(a)

Output:

0.6

6) Modulus and Assign: This operator is used to take the modulus using the left and the right operands and then assigning the result to the left operand.

Syntax:

x %= y

Example:

Python3

a = 3

b = 5

# a = a % b

a %= b

# Output

print(a)

Output:

3

7) Divide (floor) and Assign: This operator is used to divide the left operand with the right operand and then assigning the result(floor) to the left operand.

Syntax:

x //= y

Example:

Python

a = 3

b = 5

# a = a // b

a //= b

# Output

print(a)

Output:

0

8) Exponent and Assign: This operator is used to calculate the exponent(raise power) value using operands and then assigning the result to the left operand.

Syntax:

x **= y

Example:

Python

a = 3

b = 5

# a = a ** b

a **= b

# Output

print(a)

Output:

243

9) Bitwise AND and Assign: This operator is used to perform Bitwise AND on both operands and then assigning the result to the left operand.

Syntax:

x &= y

Example:

Python3

a = 3

b = 5

# a = a & b

a &= b

# Output

print(a)

Output:

1

10) Bitwise OR and Assign: This operator is used to perform Bitwise OR on the operands and then assigning result to the left operand.

Syntax:

x |= y

Example:

Python3

a = 3

b = 5

# a = a | b

a |= b

# Output

print(a)

Output:

7

11) Bitwise XOR and Assign: This operator is used to perform Bitwise XOR on the operands and then assigning result to the left operand.

Syntax:

x ^= y

Example:

Python3

a = 3

b = 5

# a = a ^ b

a ^= b

# Output

print(a)

Output:

6

12) Bitwise Right Shift and Assign: This operator is used to perform Bitwise right shift on the operands and then assigning result to the left operand.

Syntax:

x >>= y

Example:

Python3

a = 3

b = 5

# a = a >> b

a >>= b

# Output

print(a)

Output:

0

13) Bitwise Left Shift and Assign: This operator is used to perform Bitwise left shift on the operands and then assigning result to the left operand.

Syntax:

x <<= y

Example:

Python3

a = 3

b = 5

# a = a << b

a <<= b

# Output

print(a)

Output:

96

Comparison Operators

There are 6 types of comparison operators :

Yahoo Answers to Shut Down Permanently in May

1. Less Than ( < )

2. Greater Than ( > )

3. Equal To ( == )

4. Not Equal ( != )

5. Less Than or Equal To ( <= )

6. Greater Than or Equal To ( >= )

Python Comparison Operators

1. Less Than ( < )

It is used to check for the smaller value or variable containing smaller value as compared with the other number or variable. If the provided number or a variable is smaller than the given number or variable. Then, the Less Than operator will return True. Else, it will return false.

a = 10

if (a < 10)

print("Yes")

else

print("No")

Output: No

2. Greater Than ( > )

It is used to check for the greater value or variable containing greater value as compared with the other number or variable. If the provided number or a variable is greater than the given number or variable. Then, the Greater Than operator will return True. Else, it will return false.

a = 10

if (a > 10)

print("True")

else

print("False")

Output: False

3. Equal To ( == )

This Operator checks for equal values. If the entered value and given value are equal then it will return True else False.

a = 10

b = 20

if (a == b)

print("True")

else

print("False")

Output: False

4. Not Equal ( != or <> )

It is denoted by !=, this does the exact opposite of the equal to operator. It returns True if the values on either side of the operator are unequal.

print(3!=3.0)

Output: False

5. Less than or Equal to (<=)

This operator evaluates to True only if the value on the left is less than or equal to that on the right.

a = 15

b = 5

if(b <= a)

print("b is either less than or equal to a")

Output: b is either less than or equal to a

6. Greater than or Equal to (>=)

This operator evaluates to True only if the value on the left is greater than or equal to that on the right.

a = 5

b = 15

if(b >= a)

print("b is either greater than or equal to a")

Output: b is either greater than or equal to a

Membership Operators

Membership operators are operators used to validate the membership of a value. It test for membership in a sequence, such as strings, lists, or tuples.

1. in operator : The ‘in’ operator is used to check if a value exists in a sequence or not. Evaluates to true if it finds a variable in the specified sequence and false otherwise.

# Python program to illustrate

# Finding common member in list

# using 'in' operator

list1=[1,2,3,4,5]

list2=[6,7,8,9]

for item in list1:

if item in list2:

print("overlapping")

else:

print("not overlapping")

Output:
not overlapping

2. 
   Same example without using in operator:

# Python program to illustrate

# Finding common member in list

# without using 'in' operator

# Define a function() that takes two lists

def overlapping(list1,list2):

c=0

d=0

for i in list1:

c+=1

for i in list2:

d+=1

for i in range(0,c):

for j in range(0,d):

if(list1[i]==list2[j]):

return 1

return 0

list1=[1,2,3,4,5]

list2=[6,7,8,9]

if(overlapping(list1,list2)):

print("overlapping")

else:

print("not overlapping")

Output:


not overlapping

3. 
   

4. ‘not in’ operator- Evaluates to true if it does not finds a variable in the specified sequence and false otherwise.

# Python program to illustrate

# not 'in' operator

x = 24

y = 20

list = [10, 20, 30, 40, 50 ];

if ( x not in list ):

print("x is NOT present in given list")

else:

print("x is present in given list")

if ( y in list ):

print("y is present in given list")

else:

print("y is NOT present in given list")

Identity operators

n Python are used to determine whether a value is of a certain class or type. They are usually used to determine the type of data a certain variable contains.

There are different identity operators such as

1. ‘is’ operator – Evaluates to true if the variables on either side of the operator point to the same object and false otherwise.

# Python program to illustrate the use

# of 'is' identity operator

x = 5

if (type(x) is int):

print("true")

else:

print("false")

Output:
true

2. 
   

3. ‘is not’ operator – Evaluates to false if the variables on either side of the operator point to the same object and true otherwise.

# Python program to illustrate the

# use of 'is not' identity operator

x = 5.2

if (type(x) is not int):

print("true")

else:

print("false")

4. 
   Output:
   true

Bitwise Operators

Bitwise AND operator: Returns 1 if both the bits are 1 else 0.

Example:

a = 10 = 1010 (Binary)

b = 4 = 0100 (Binary

a & b = 1010

&

0100

= 0000

= 0 (Decimal)

Bitwise or operator: Returns 1 if either of the bit is 1 else 0.

Example:

a = 10 = 1010 (Binary)

b = 4 = 0100 (Binary

a | b = 1010

|

0100

= 1110

= 14 (Decimal)

Bitwise not operator: Returns one’s compliement of the number.

Example:

a = 10 = 1010 (Binary)

~a = ~1010

= -(1010 + 1)

= -(1011)

= -11 (Decimal)

Bitwise xor operator: Returns 1 if one of the bit is 1 and other is 0 else returns false.

Example:

a = 10 = 1010 (Binary)

b = 4 = 0100 (Binary

a & b = 1010

^

0100

= 1110

= 14 (Decimal)

Python3

# Python program to show

# bitwise operators

a = 10

b = 4

# Print bitwise AND operation

print("a & b =", a & b)

# Print bitwise OR operation

print("a | b =", a | b)

# Print bitwise NOT operation

print("~a =", ~a)

# print bitwise XOR operation

print("a ^ b =", a ^ b)

Output:

a & b = 0

a | b = 14

~a = -11

a ^ b = 14

Shift Operators

These operators are used to shift the bits of a number left or right thereby multiplying or dividing the number by two respectively. They can be used when we have to multiply or divide a number by two.

Bitwise right shift: Shifts the bits of the number to the right and fills 0 on voids left as a result. Similar effect as of dividing the number with some power of two.

Example:

Example 1:

a = 10

a >> 1 = 5

Example 2:

a = -10

a >> 1 = -5

Bitwise left shift: Shifts the bits of the number to the left and fills 0 on voids left as a result. Similar effect as of multiplying the number with some power of two.

Example:

a = 5 = 0000 0101

b = -10 = 1111 0110

a << 1 = 0000 1010 = 10

a << 2 = 0001 0100 = 20

b << 1 = 0000 1010 = -20

b << 2 = 0001 0100 = -40

Python3

# Python program to show

# shift operators

a = 10

b = -10

# print bitwise right shift operator

print("a >> 1 =", a >> 1)

print("b >> 1 =", b >> 1)

a = 5

b = -10

# print bitwise left shift operator

print("a << 1 =", a << 1)

print("b << 1 =", b << 1)

Output:

a >> 1 = 5

b >> 1 = -5

a << 1 = 10

b << 1 = -20

Bitwise Operator Overloading

Operator Overloading means giving extended meaning beyond their predefined operational meaning. For example operator + is used to add two integers as well as join two strings and merge two lists. It is achievable because ‘+’ operator is overloaded by int class and str class. You might have noticed that the same built-in operator or function shows different behavior for objects of different classes, this is called Operator Overloading.

Below is a simple example of Bitwise operator overloading.

Python3

# Python program to demonstrate

# operator overloading

class Geek():

def __init__(self, value):

self.value = value

def __and__(self, obj):

print("And operator overloaded")

if isinstance(obj, Geek):

return self.value & obj.value

else:

raise ValueError("Must be a object of class Geek")

def __or__(self, obj):

print("Or operator overloaded")

if isinstance(obj, Geek):

return self.value | obj.value

else:

raise ValueError("Must be a object of class Geek")

def __xor__(self, obj):

print("Xor operator overloaded")

if isinstance(obj, Geek):

return self.value ^ obj.value

else:

raise ValueError("Must be a object of class Geek")

def __lshift__(self, obj):

print("lshift operator overloaded")

if isinstance(obj, Geek):

return self.value << obj.value

else:

raise ValueError("Must be a object of class Geek")

def __rshift__(self, obj):

print("rshift operator overloaded")

if isinstance(obj, Geek):

return self.value & obj.value

else:

raise ValueError("Must be a object of class Geek")

def __invert__(self):

print("Invert operator overloaded")

return ~self.value

# Driver's code

if __name__ == "__main__":

a = Geek(10)

b = Geek(12)

print(a & b)

print(a | b)

print(a ^ b)

print(a << b)

print(a >> b)

print(~a)

Output:

And operator overloaded

8

Or operator overloaded

14

Xor operator overloaded

8

lshift operator overloaded

40960

rshift operator overloaded

8

Invert operator overloaded

-11

BOOLEAN

Booleans represent one of two values: True or False.

Boolean Values

In programming you often need to know if an expression is True or False.

You can evaluate any expression in Python, and get one of two answers, True or False.

When you compare two values, the expression is evaluated and Python returns the Boolean answer:

Example

print(10 > 9)

print(10 == 9)

print(10 < 9)

Try it Yourself »

When you run a condition in an if statement, Python returns True or False:

Example

Print a message based on whether the condition is True or False:

a = 200

b = 33

if b > a:

print("b is greater than a")

else:

print("b is not greater than a")

Try it Yourself »

Evaluate Values and Variables

The bool() function allows you to evaluate any value, and give you True or False in return,

Example

Evaluate a string and a number:

print(bool("Hello"))

print(bool(15))

Try it Yourself »

Example

Evaluate two variables:

x = "Hello"

y = 15

print(bool(x))

print(bool(y))

Try it Yourself »

Most Values are True

Almost any value is evaluated to True if it has some sort of content.

Any string is True, except empty strings.

Any number is True, except 0.

Any list, tuple, set, and dictionary are True, except empty ones.

Example

The following will return True:

bool("abc")

bool(123)

bool(["apple", "cherry", "banana"])

Try it Yourself »

Some Values are False

In fact, there are not many values that evaluate to False, except empty values, such as (), [], {}, "", the number 0, and the value None. And of course the value False evaluates to False.

Example

The following will return False:

bool(False)

bool(None)

bool(0)

bool("")

bool(())

bool([])

bool({})

Try it Yourself »

One more value, or object in this case, evaluates to False, and that is if you have an object that is made from a class with a __len__ function that returns 0 or False:

Example

class myclass():

def __len__(self):

return 0

myobj = myclass()

print(bool(myobj))

Try it Yourself »

Functions can Return a Boolean

You can create functions that returns a Boolean Value:

Example

Print the answer of a function:

def myFunction() :

return True

print(myFunction())

Try it Yourself »

You can execute code based on the Boolean answer of a function:

Example

Print "YES!" if the function returns True, otherwise print "NO!":

def myFunction() :

return True

if myFunction():

print("YES!")

else:

print("NO!")

Try it Yourself »

Python also has many built-in functions that return a boolean value, like the isinstance() function, which can be used to determine if an object is of a certain data type:

Example

Check if an object is an integer or not:

x = 200

print(isinstance(x, int))