Operators and Control Statements in Python

Python Programming
Dr.A.Rajeswari, M.Tech, Ph.D
Assistant Professor II
Department of Computer Science
and Engineering
Velammal Engineering College

Operators and Operands
2
Python Programming - Operators and Conditional Statements by Dr.A.Rajeswari,AP-II/CSE,VEC
• Operators are symbols that instruct the
computer to perform a task
• Operands are expressions or values on which
an operator operates or works
• Example: a+b
a,b are operands
+ is the operator

Based on Number of Operands
• Unary Operator- one operand
Example: -a
• Binary Operator- Two operand
Example: a+5
• Ternary Operator- Three operand
conditional operator (?:)
Example: a if a>b else b
3

Types of Operator
4
Python language supports the following types of operators.
• Arithmetic Operators
• Comparison (Relational) Operators
• Assignment Operators
• Logical Operators
• Bitwise Operators
• Membership Operators
• Identity Operators

Arithmetic Operators
Arithmetic operators take numerical values (either literals or variables) as their
operands and return a single numerical value. Assume variable a holds 30(a=30)
and variable b holds 18(b=18) then
Python Programming - Operators and Conditional Statements by Dr.A.Rajeswari,AP-II/CSE,VEC 5

Example Code
a,b=30,18
print('a=',a)
print('b=',b)
print('na+b=',a+b)
print('a-b=',a-b)
print('a*b=',a*b)
print('a/b=',a/b)
print('a%b=',a%b)
print('a**b=',a**b)
print('a//b=',a//b)

Comparison Operators
Also called a relational operator is a
programming language construct or operator
that tests or defines some kind of relation
between two entities. relational operators
return the integers 0 or 1, where 0 stands for
false and 1 stands for true
Assume variable a holds 30 and variable b holds
18,

Example Code
a,b=30,18
print('a=',a)
print('b=',b)
print('na>b is ',a>b)
print('a<b is ',a<b)
print('a==b is ',a==b)
print('a!=b is ',a!=b)
print('na<=b is ',a<=b)
print('na>=b is ',a>=b)

Assignment Operators
Assume variable a holds 30 and variable b holds 18, and c is a variable

a,b=30,18
print('a=',a)
print('b=',b)
c=a+b
print('c=a+b=',c)
c+=a #c=c+a c=48+30=78 now c is 78
print('c=c+a=',c)
c-=a #c=c-a c=78-30=48 now c is 48

Cont..
print('c=c-a=',c)
c*=a #c=c*a c=48*30=1440 now c is 1440
print('c=c*a=',c)
c/=a #c=c/a c=1440/30=48 now c is 48
print('c=c/a=',c)
c%=a #c=c%a c=48%30=18 now c is 18
print('c=c%a=',c)
c**=a #c=c**a c=18^30=4.551715960790334e+37 now
c is 4.551715960790334e+37
print('c=c^a=',c)
c//=a #c=c//a
c=4.551715960790334e+37//30=1.517238653596778e+3 6 now
c is 1.517238653596778e+36
print('c=c//a',c)

Bitwise Operators
Bitwise operator works on bits and performs bit
by bit operation
and gate

OR and NOT Gate

X-OR Gate

Assume if a = 60; and b = 13; Now in binary
format they will be as follows
a=0011 1100 b=0000 1101

<< Binary Left Shift
• a << 2 Returns a with the bits shifted to the
left by 2 places (and new bits on the right-
hand-side are zeros).
• a<<2 0 0 1 1 1 1 0 0<<2 1 1 1 1 0 0 0 0 240
>> Binary Right Shift
• a >> 2 Returns a with the bits shifted to the
right by 2 places (and new bits on the left-
hand-side are zeros).
• a>>2 0 0 1 1 1 1 0 0>>2 0 0 0 0 1 1 1 1 15

Example Code
a=0b00111100
b=0b00001101
print('a=',bin(a),'b=',bin(b))
print('a or b is=',bin(a|b))
print('a and b is=',bin(a&b))
print('a xor b is=',bin(a^b))
print('Ones Complement of a=',bin(~a))
print('a Left Shift by 2 is',bin(a<<2))
print('a Right Shift by 2 is',bin(a>>2))

Logical Operators
here are following logical operators supported by Python language. Assume
variable a holds 10 and variable b holds 20 then

Example Code
a,b=10,20
c=c=(a>11)and (b>10) # 0 and 1 so result is false
print(c)
c=(a>11)or(b>10) # 0 or 1 so result is true print(c)
a,b=10,20
c=not((a>11)and (b>10)) # not(0 and 1)=not(false) so
result is true
print(c)

Membership Operators
Python’s membership operators test for membership in a sequence, such as
strings, lists, or tuples. There are two membership operators as explained
below

Example Code
a=[1,2,3,4,5,6,7,8,9,10] # a is a list
print(3 in a) # 3 in list a so result is true
print(20 in a) # 20 not in list a so result is false
print(3 not in a) # 3 not in list a ,(but 3 in list a) so
result is false
print(20 not in a) # 20 not in list a ,(but 20 not
in list a ) so result is true

Identity Operators
Identity operators compare the memory locations of two objects. There are two
Identity operators as explained below
Example Code
a,b=10,100
print(a is b)
print(a is not b)

ALL Python Operators Precedence

Cont..

Quiz
https://realpython.com/quizzes/python-
operators-expressions/

Control Statement
Flow of control through any given program is
implemented with three basic types of control
structures: Sequential, Selection and Repetition.

Decision Making Statement
Decision making statements in programming languages
decides the direction of flow of program execution.
Decision making statements available in python are:
• if statement
• if..else statements
• nested if statements
• if-elif ladder

if Statement
Syntax:
if condition:
# Statements to
execute if
# condition is true
if condition:
statement1
statement2
# Here if the condition
is true, if block
# will consider only
statement1 to be
inside
# its block.

Example Code
i = 10
if (i > 15):
print ("10 is less than 15")
print ("I am Not in if")
Output:
I am Not in if

if- else Statement
Syntax:
if (condition):
# Executes this block if
# condition is true
else:
# Executes this block if
# condition is false

Example Code
i = 20
if (i < 15):
print ("i is smaller than 15")
print ("i'm in if Block")
else:
print ("i is greater than 15")
print ("i'm in else Block")
print ("i'm not in if and not in else
Block")
Output
i is greater than 15
i'm in else Block
i'm not in if and not in else
Block

Nested-if Statement
Syntax:
if (condition1):
# Executes when condition1 is
true
if (condition2):
# Executes when
condition2 is true
# if Block is end here
# if Block is end here

Example Code
i = 10
if (i == 10):
# First if statement
if (i < 15):
print ("i is smaller than 15")
# Nested - if statement
# Will only be executed if
statement above
# it is true
if (i < 12):
print ("i is smaller than 12 too")
else:
print ("i is greater than 15")
Output:
i is smaller than 15
i is smaller than 12 too

If-elif-else ladder
Syntax
if (condition):
statement
elif (condition):
statement
.
.
else:
statement

Example Code
i = 20
if (i == 10):
print ("i is 10")
elif (i == 15):
print ("i is 15")
elif (i == 20):
print ("i is 20")
else:
print ("i is not present")
Output
i is 20

Example Programs
• Odd or Even Number
• Positive or Negative Number
• Leap year or not
• Greatest of two numbers and three numbers
• Eligibility for voting

Quiz
https://realpython.com/quizzes/python-
conditional-statements/

Operators and Control Statements in Python

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