Python: Operators

Operators

•  Operands are special symbols that are used in computations. For example +,‒,* and / are used for performing arithmetic operations.

•  The values that the operator uses for performing computation are called operands.

•  Various operators used in python are described as follows.

1. Arithmetic Operators 

2. Comparison Operators 

3. Logical Operators 

4. Bitwise Operators 

5. Assignment Operator 

6. Membership Operator 

7. Identity Operator 

8. Modulus Operator 

9. String Operators

 

1. Arithmetic Operators

These operators are used for performing arithmetic operations.

For example

In [8]: 10+20

Out [8]: 30

In [9]: 20‒10

Out [9]: 10

In [10]: 2**3

Out[10]: 8

In [11]: 9//2

Out[11]: 4

 

2. Comparison Operators

The operators compare the values and establish the relationship among them.

Operators

== : If two values are equal then the condition becomes true.

!= :  If two operands are not equal then the condition becomes true.

<> : This is similar to !=. That means if two values are not equal then it returns true.

< : This is less than operator. If left operand is less than the right operator then the return value is true.

> : This is greater than operator. If left operand is greater than the right operator then the return value is true.

<= : This is less than equal to operator. If left operand is less than the right operator or equal to the right operator then the return value is true.

>= : This is greater than equal to operator. If left operand is less than the right operator or equal to the right operator then the return value is true.

For example ‒

In [1]: 10<20

True

In [2]: 10<=10

True

In [3]: 20>10

True

In [4]: 20>=10

True

 

3. Logical Operators

There are three types of logical operators and or, not.

Operators

and: If both the operands are true then the entire expression is true.  Example: a and b

or: If either the first or second operand is true. Example: a or b

not: If the operand is false then the entire expression is true. Example: not a

For example

In [1]: a=True

b=False

a and b

False

In [2]: a or b

True

In [3]: not a

False

 

4. Bitwise Operators

Bitwise operators work on the bits of the given value. These bits are binary numbers i.e. 0

or1.

For example: The number 2 is 010, 3 is 011.

 

5. Assignment Operator

The assignment operator is used to assign the values to variables. Following is a list of assignment operators.

Operators  ‒     Example and meaning

=     :   This is an operator using which values is assigned to a variable.a = 5

+=     :   a+ 5 means a = a+5

‒=     :   a‒ = 5 means a = a‒5

Similarly *=, /= operators are used for performing arithmetic multiplication and division operation.

Example:1

Write a program in python to print area and perimeter of a circle.

Solution :

In [12]: print("Enter radius of a circle: ")

r = float(input())

Enter radius of a circle:

10

In [13]: PI = 3.14

area PI* r *r

perimeter = 2.0*PI*r

print("Area of circle = ", area)

print("Perimeter of Circle = ",perimeter)

Area of circle = 314.0

Perimeter of Circle = 62.800000000000004

Example:2

Write a program to find area and perimeter of parallelogram.

Solution:

Formula for finding area and perimeter of parallelogram is

Area= b*h

Perimeter = 2*b+2*w

We can write the python program using above formula

areaDemo1.py

print("Enter height(h): ")

h=float(input())

print("Enter base(b): ")

b=float(input())

print("Enter width(w): ")

w=float(input())

area= b*h

perimeter= (2.0*b)+(2.0*w)

print("Area of Parallelogram = ",area);

print("Perimeter Parallelogram = ",perimeter)

Output

Enter height (h):

10

Enter base(b):

20

Enter width(w):

15

Area of Parallelogram = 200.0

Perimeter Parallelogram = 70.0

Example:3

Write a program to convert fahrenheit to celsius.

Solution:

We will use the following formula for conversion

Celsius = (Fahrenheit ‒ 32)/1.8

Temp.py

print("Enter Fahrenheit")

f=float(input())

c= (f‒32)/1.8

print("Celsius = ",c)

Output

Enter Fahrenheit

95.5

Celsius = 35.2777

6. Membership Operator

There are two types of membership operators ‒ in and not in.

These operators are used to find out whether a value is a member of a sequence such as string or list.

Operators

in ‒ It returns true if a sequence with specified value is present in the object.

not in ‒ It returns true if a sequence with specified value is not present in the object.

Following screenshot shows the use of in and non in operators.

In [1]: Color = ['red', 'blue', 'green']

print("blue" in Color)

True

In [2]: print("yellow" in Color)

False

In [3]: print("yellow" not in Color)

True

Explanation:

1) In example, we have created a list of colors.

2) The members of color list are "red","blue" and "green".

3) As "blue" is member of color list, it returns true for while testing with membership operator in operator.

4) As "yellow" is not a member of color list, it returns false for in operator and true for not

in operator.

 

7. Identity Operator

The 'is' operator returns true if both the operands point to same memory location. Similarly 'is not' operator returns true if both the operands point to different memory locations.

In [4]:

color1 = ["red", "blue", "green"]

color2 = ["red", "blue", "green"]

color3 = color1

print(color1 is color2)

False

In [5]:

print(color1 is color3)

True

Similarly,

In [6]: print(color1 is not color2)

True

Explanation: In above demonstration,

1) We have created two lists color1 and color2.

2) Although the contents of the lists are exactly the same, their memory locations are different. Hence color1 is color2 becomes false,

3) As color3 is a new variable to which we assign color1, then they point to the same memory location. Hence color1 is color3 returns true.

 

8. Modulus Operator

The % operator is a modulo operator that gives the remainder from the division of the first argument by the second.

For example ‒

In[1]: 10%3

1

In[2]: 10.10%3.3

0.20000000000000018

The operator // is used for floor division. This division returns the integral part of the quotient.

For example ‒

In[1]: 10//3.5

2.0

Example:4

Write a program in python to convert given time into minutes and seconds.

For example ‒ if user inputs 260 seconds then the output should be 4 minute and 20 seconds.

 [Use // and % operators].

Solution :

timeDemo.py

print("Enter time: ")

time‒float(input())

minutes = time//60

seconds time % 60

print("Minutes are: ",minutes)

print("Seconds are: ",seconds)

Output

In [1]:

import timeDemo

Enter time:

260

Minutes are: 4.0

Seconds are: 20.0

 

9. String Operators

String is a collection of characters.

In python it is possible to perform the concatenation and repetition operations on strings using the operators like + and *.

For example ‒

In[1]: str1="Hello"

        str2="friend"

        str1+str2

'Hellofriend'

In[2]: "welcome"*2

'welcomewelcome'

 

Review Questions

1. Appraise the arithmetic operators in python with an example.

2. State about logical operators available in python language with example.

3. Summarize the precedence of mathematical operators in python.