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Introduction to Python

Table of Contents

Chapter 19 - Nested Selection Structures

  • Authors
  • Ms. Samavi Salman
  • Dr. Rao Muhammad Adeel Nawab
  • Supporting Material

Nested IF in Python

  • Nested IF
  • Definition
    • if statements inside if statements, this is called nested if statements
  • Purpose
    • The main purpose of Nested if statements are often used when you must test a combination of conditions before deciding on the proper action
  • Importance
    • Nested-if statement is also the most important and easiest concept of control flow statements. This statement is very helpful, while or when more than one condition needs to be checked based on the problem
  • Situation to Use
    • There may be a situation when you want to check for another condition after a condition resolves to true. In such a situation, you can use the nested if construct
  • Flowchart – Nested IF Statement
  • Syntax – Nested IF 
				
					'''
if Condition is True the block will be executed otherwise the control will move to the endif statement
'''

if condition: 
    if condition:
        <statement(s)01>
        <statement(s)02>
        <statement(s)03>
        ….
        <statement(s)N>
    endif
endif
  • Syntax – IF - ELIF - ELSE Statement 
				
					'''
if Condition is True the block will be executed otherwise the control will move to the elif statement if the elif condition is False the else block will be executed.
'''

if condition: 
    <statement(s)01>
    <statement(s)02>
    <statement(s)03>
    ….
    <statement(s)N>
elif condition:
    <statement(s)01>
    <statement(s)02>
    <statement(s)03>
    ….
    <statement(s)N>
else:
    <statement(s)01>
    <statement(s)02>
    <statement(s)03>
    ….
    <statement(s)N>
endif
  • Flowchart – IF - ELIF - ELSE Statement
  • Example 1 – IF - ELSE Statement
Completely and Correctly Understand a Task
Task Description
  • Write a Python Program which takes an Integer Number as Input (from User) and makes a decision whether it’s a Positive Number or a Negative Number? 
Sample Outputs

Sample Output 01

Enter an Integer Number: 100

100 is a Positive Number 

———————————————–

Sample Output 02

Enter an Integer Number: 100

-1 is a Negative Number 

———————————————–

Sample Output 03

Enter an Integer Number: 0

Number is ZERO

Plan and Design Solution to the Task
Input-Processing-Output
  • Input
    • Data
      • An Integer Number
    • Instruction(s)
      • Make a Decision – Whether the Input Integer Number is Positive or Negative? 
  • Output
    • Display a Message (on the Output Screen) whether the Input Integer Number is Positive or Negative
  • Processing
    • Use Conditions for Decision Making – To check whether the Integer Number is Positive or Negative?
      • Condition for Positive Number – number > 0
      • Condition for Positive Number – number < 0
      • Use print() Function  – To display the Message (on the Output Screen) whether the Integer Number is Positive or Negative?
Pseudo Code

Step 1: Start

Step 2: Input – number (Integer Value)

Step 3: if number is greater than 0

                    Print – Positive Number

Step 5: elif number is less than 0

                    Print – Negative Number

Step 6: else

                    Print – ZERO

             endif

Step 7: Stop 

Flow Chart
Implementation in Python
Code
				
					'''
__author__   = Ms. Samavi Salman
__copyright__= Copyright I 2020 Ms. Samavi Salman
__license__  = Public Domain
__version__  = 1.0
'''

'''
The main purpose of this Program is to take an Integer Number as Input from User and check whether it’s a Positive Number or a Negative Number?
'''

try:
    # Take an Integer Number as Input from User
    number = int(input("Enter an Integer Number: "))

    # Decision Making - Check whether Condition is True or False 
    if number > 0:
        print(number, "is a Positive Number")
    elif number < 0:
        print(number, "is Negative Number")
    else:
        print("Number is ZERO")

except ValueError:
    print("Sorry !!!. Invalid Input. Please enter Integer Number")
Execution of Code (Dry Run)
Python Statement
Calculations
Variable(s)
Output Screen
number = int(input(“Enter an Integer Number: “)) number = -100Enter an Integer Number: -100
if number > 0:

Decision Making – Check Whether Condition is True or False 

number > 0

-100 > 0

False (i.e., Statement(s) after if-Statement will not be executed)

number = -100Enter an Integer Number: -100
print(number, “is a Positive Number”)This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)number = -100Enter an Integer Number: -100
elif number < 0:

Decision Making – Check Whether Condition is True or False 

number < 0

-100 < 0

True (i.e., Statement(s) after if-Statement will be executed)

number = -100Enter an Integer Number: -100
print(number, “is a Negative Number”)This Statement will be executed because Condition is True in above if-Statement (see Output Screen)number = -100

Enter an Integer Number: -100

-100 is a Negative Number

Output of Code 

Enter an Integer Number: -100

-100 is a Negative Number

  • Example 2 – IF - ELSE Statement

 

Completely and Correctly Understand a Task
Task Description
  • Write a Python Program which takes two Numbers and an Arithmetic Operator as Input (from User) and performs Operation on Operands (Two Numbers) using Operator 
Sample Outputs

Sample Output 01

Enter First Number: 5.2

Enter Second Number: 3

Enter Operator (+, -, *, /, **): *

5.2 * 3 = 15.6

——————————————-

Sample Output 02

Enter First Number: 10

Enter Second Number: 3

Enter Operator (+, -, *, /, **): **

10 ** 3 = 1000

——————————————-

Sample Output 03

Enter First Number: 4.35

Enter Second Number: 3.25

Enter Operator (+, -, *, /, **): /

4.35 / 3.25 = 1.33

——————————————-

Sample Output 04

Enter First Number: 10

Enter Second Number: 30

Enter Operator (+, -, *, /, **): –

10 – 30 = -20

——————————————-

Sample Output 05

Enter First Number: 100

Enter Second Number: 500

Enter Operator (+, -, *, /, **): +

100 + 500 = 600

Plan and Design Solution to the Task
Input-Processing-Output
  • Input
    • Data
      • Two Numbers 
      • An Operator (+, -, *, /, **)
    • Instruction(s)
      • Take Two Numbers as Input form User
      • Take an Operator as Input from User
      • Make a Decision – whether Operator is +, -, *, / or **
    • Based on Value of Operator Add, Subtract, Multiply, Divide or (Take) Exponent of Two Numbers 
  • Output
    • Display the result obtained by applying Operator on Operands (Two Numbers) on the Output Screen 
  • Processing
    • Use Conditions for Decision Making – To check what Operator is Input by User
      • Condition for + Operator – if operator == ‘+’
      • Condition for – Operator – elif operator == ‘-‘
      • Condition for * Operator – elif operator == ‘*’
      • Condition for / Operator – elif operator == ‘/’
      • Condition for ** Operator – elif operator == ‘**’
      • Use print() Function – To display the result obtained by applying Operator on Operands (Two Numbers) on the Output Screen
Pseudo Code

Step 1: Start

Step 2: Input – number1

Step 3: Input – number2

Step 4: Input – operator (Arithmetic Operator)

Step 5: if operator == ‘+’ 

                    Print – Sum of number1 and number2

Step 6: elif operator == ‘-‘

          Print – Subtraction of number2 from number1

Step 7: elif operator == ‘*’ 

          Print – Product (Multiplication) of number1 and number2

Step 8: elif operator == ‘/’ 

          Print – Division of number1 by number2

Step 9: elif operator == ‘**’ 

          Print – Exponent of number1 with number2

                endif

Step 10: Stop

Flow Chart
Implementation in Python
Code
				
					'''
__author__   = Ms. Samavi Salman
__copyright__= Copyright I 2020 Ms. Samavi Salman
__license__  = Public Domain
__version__  = 1.0
'''

'''
The main Purpose of the Program is to take two Numbers and an Operator as Input from User and perform Arithmetic Operation on Operands (Two Numbers) based on Value of Operator 
'''

try:
 # Take Two Numbers (Integers or Float) as Input from User

    number1 = float(input("Enter First Number: "))
    number2 = float(input("Enter Second Number: "))

    
 # Take Operator as input from User
    operator = input("Enter an Operator: ")

 # Decision Making – Check whether Value of Operator is + or not 
    if operator == '+':
        print(number1,"+",number2,"=", number1 + number2)
    elif operator == '-':
        print(number1,"-",number2,"=", number1 - number2)
    elif operator == '*':

        print(number1,"*",number2,"=", number1 * number2)
    elif operator == '/':
        print(number1,"/",number2,"=", number1 / number2)                
    elif operator == '**':
        print(number1,"**",number2,"=", umber1 ** number2)
    else: 
        print("Invalid Operator!")

except ValueError:
        print("Sorry !!!. Invalid Input. Please enter Integer Number")

except ZeroDivisionError:
    print("Sorry !!!. Invalid Division. Please enter Integer Number other than ZERO")
Execution of Code
Python Statement
Calculations
Variable(s)
Output Screen
number1 = float(input(“Enter First Number: “)) number1 = 5Enter First Number: 5
number2 = float(input(“Enter Second Number: “)) 

number1 = 5

number2 = 2

Enter First Number: 5

Enter Second Number: 2

operator = input(“Enter an Operator: “) 

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

if operator == ‘+’:

Decision Making – Check Whether Condition is True or False 

operator == +

** == +

False (i.e., Statement(s) after if-Statement will not be executed)

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

print(number1,”+”,number2,”=”, number1 + number2)This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

elif operator == ‘-‘:

Decision Making – Check Whether Condition is True or False 

** == –

False (i.e., Statement(s) after if-Statement will not be executed)

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

print(number1,”-“,number2,”=”, number1 – number2)This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

elif operator == ‘*’:

Decision Making – Check Whether Condition is True or False 

** == *

False (i.e., Statement(s) after if-Statement will not be executed)

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

print(number1,”*”,number2,”=”, number1 * number2)This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

elif operator == ‘/’:

Decision Making – Check Whether Condition is True or False 

** == /

False (i.e., Statement(s) after if-Statement will not be executed)

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

print(number1,”/”,number2,”=”, number1 / number2)This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 5

number2 = 2

operator = **

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

elif operator == ‘**’:

Decision Making – Check Whether Condition is True or False 

** == **

True (i.e., Statement(s) will be executed because the previous condition is true)

number1 = 5

number2 = 2

operator = **

5 ** 2 = 25

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

print(number1,”**”,number2,”=”, number1 ** number2)This Statement will be executed because Condition is True in above elif-Statement (see Output Screen)

number1 = 5

number2 = 2

operator = **

5 ** 2 = 25

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

5 ** 2 = 25

Output of Code 

Enter First Number: 10

Enter Second Number: 30

Enter an Operator: /

10 / 30 = 0.33

  • Example 3 – IF - ELSE Statement
Completely and Correctly Understand a Task
Task Description
  • Write a Python Program which takes an Integer Number as Input (from User) and makes a decision whether it’s a Positive Number or a Negative Number with the following conditions?
    • Positive and Even Number
    • Positive and Odd Number
    • Neither Positive nor Negative
    • Negative and Even Number
    • Negative and Odd Number
Sample Outputs

Sample Output 01

Enter an Integer Number: 5000

5000 is a Positive Number

And 5000 is an Even Number

———————————————————-

Sample Output 02

Enter an Integer Number: 7000

5000 is a Positive Number

And 7000 is an Odd Number

———————————————————-

Sample Output 03

Enter an Integer Number: 0

ZERO is a Neutral Number

———————————————————-

Sample Output 04

Enter an Integer Number: -50.45

Sorry !!!. Invalid Input. Please enter Integer Number

———————————————————-

Sample Output 05

Enter an Integer Number: ambition

Sorry !!!. Invalid Input. Please enter Integer Number

Plan and Design Solution to the Task
Input-Processing-Output
  • Input
    • Data
      • An Integer Number
    • Instruction(s)
      • Make a Decision – Whether the Input Integer Number is Positive and Even Number
        • Positive and Odd Number
        • Neither Positive nor Negative
        • Negative and Even Number
        • Negative and Odd Number
        • Number is equal to ZERO
  • Output
    • Display a Message (on the Output Screen) whether the Input Integer Number is 
      • Positive and Odd Number
      • Neither Positive nor Negative
      • Negative and Even Number
      • Negative and Odd Number
      • Number is equal to ZERO
  • Processing
    • Use Conditions for Decision Making – To check whether the Integer Number meets the following conditions?
      • Condition for Positive Number – number > 0
      • Condition for Even Number – number % 2 == 0
      • Condition for Odd Number – number % 2 == 1
      • Condition for Negative Number – number < 0
      • Condition for Even Number – number % 2 == 0
      • Condition for Odd Number – number % 2 == 1
      • Condition for ZERO – number == 0
      • Use print() Function  – To display the Message (on the Output Screen) whether the Integer Number is Positive and Odd Number
      • Neither Positive nor Negative
      • Negative and Even Number
      • Negative and Odd Number
      • Number is equal to ZERO
Pseudo Code

Step 1: Start

Step 2: Input – number (Integer Value)

Step 3: if number is greater than 0

                    Print – Positive Number

                    If number % 2 == 0

                          Print – Even Number

                    else

                          Print – Odd Number

          elif number is equal to 0

               Print – ZERO

          else

               if number % 2 == 0

                     Print – Even Number

          else

                     Print – Odd Number

          endif

Step 4: Stop 

Flow Chart
Implementation in Python
Code
				
					'''
__author__   = Ms. Samavi Salman
__copyright__= Copyright I 2020 Ms. Samavi Salman
__license__  = Public Domain
__version__  = 1.0
'''

'''
The main purpose of this Program is to take an Integer Number as Input from User and check whether it’s a Positive Number or a Negative Number also that whether it’s an Even number, Odd number or ZERO?
'''

    # Take an Integer Number as Input from User
    number = int(input("Enter an Integer Number: "))
    
    # Decision Making - Check whether Condition is True or False 
    if number > 0:
        print(number, "is a Positive Number")
        
        if number % 2 == 0:
            print("And", number, "is an Even Number")
        else:
            print(number, "is an Odd Number")

    # Decision Making - Check whether Condition is True or False 
    elif number == 0:
        print("ZERO is a Neutral Number")

    else:
        print(number, "is a Negative Number")

        if number % 2 == 0:
            print(number, "is an Even Number")
        else:
            print("And", number, "is an Odd Number")

except ValueError:
    print("Sorry !!!. Invalid Input. Please enter Integer Number")
Execution of Code (Dry Run)
Python Statement
Calculations
Variable(s)
Output Screen

try:

   

number = int(input(“Enter an Integer Number: “))

 

number = -3

Enter an Integer Number: -3

if number > 0:

Decision Making – Check Whether Condition is True or False 

number > 0

-3 > 0

False (i.e., Statement(s) will be executed after if-Statement)

number = -3

Enter an Integer Number: -3

print(number, “is a Positive Number”)

This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number = -3

Enter an Integer Number: -3

if number % 2 == 0:

This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number = -3

Enter an Integer Number: -3

print(“And”, number, “is an Even Number”)

 

number = -3

Enter an Integer Number: -3

else:

This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number = -3

Enter an Integer Number: -3

print(number, “is an Odd Number”)

 

number = -3

Enter an Integer Number: -3

elif number == 0:

Decision Making – Check Whether Condition is True or False 

-3 == 0

-3 < 0

False (i.e., Statement(s) will be executed after if-Statement)

number = -3

Enter an Integer Number: -3

print(“ZERO is a Neutral Number”)

This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)

number = -3

Enter an Integer Number: -3

else:

 

number = -3

Enter an Integer Number: -3

print(number, “is a Negative Number”)

This Statement will be executed because Condition is True in above else-Statement (see Output Screen)

number = -3

Enter an Integer Number: -3

-3 is a Negative Number

if number % 2 == 0:

Decision Making – Check Whether Condition is True or False 

-3 % 2 == 0

False (i.e., Statement(s) will be executed after if-Statement)

number = -3

Enter an Integer Number: -3

-3 is a Negative Number

print(number, “is an Even Number”)

This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)

number = -3

Enter an Integer Number: -3

-3 is a Negative Number

else:

 

number = -3

Enter an Integer Number: -3

-3 is a Negative Number

print(“And”, number, “is an Odd Number”)

This Statement will be executed because Condition is True in above else-Statement (see Output Screen)

number = -3

Enter an Integer Number: -3

-3 is a Negative Number

And -3 is an Odd Number

except ValueError:

   

print(“Sorry !!!. Invalid Input. Please enter Integer Number”)

   
Output of Code

Enter an Integer Number: -3

-3 is a Negative Number

And -3 is an Odd Number

  • Example 4 – IF - ELSE Statement
Completely and Correctly Understand a Task
Task Description
  • Write a Python Program which takes three Integer Numbers as Input (from User) and makes a decision makes a decision: (1) First Number is greater than the Second Number, (2) First Number is greater than the Third Number, (3) Second Number is greater than First Number, or (4) Second Number is greater than Third Number? 
Sample Outputs

Sample Output 01

Enter First Number: 1200

Enter Second Number: 1000

Enter Third Number: 1100

number1 is greater than number3

number1 is greater than number2

———————————————————-

Sample Output 02

Enter First Number: 1000

Enter Second Number: 1200

Enter Third Number: 1100

number2 is greater than number1

number2 is greater than number3

———————————————————-

Sample Output 03

Enter First Number: 1100

Enter Second Number: 1000

Enter Third Number: 1200

number1 is less than number3

number1 is greater than number2

———————————————————-

Sample Output 04

Enter First Number: 1000

Enter Second Number: 1000

Enter Third Number: 1000

number1,number2 and number3 are equal

———————————————————-

Sample Output 05

Enter First Number: 12.0

Enter Second Number: 10.0

Enter Third Number: 11.0

number1 is greater than number3

number1 is greater than number2

———————————————————-

Sample Output 06

Enter First Number: 10.0

Enter Second Number: 12.0

Enter Third Number: 11.0

number2 is greater than number1

number2 is greater than number3

———————————————————-

Sample Output 07

Enter First Number: 11.0

Enter Second Number: 10.0

Enter Third Number: 12.0

number1 is less than number3

number1 is greater than number2

———————————————————-

Sample Output 08

Enter First Number: 10.0

Enter Second Number: 10.0

Enter Third Number: 10.0

number1,number2 and number3 are equal

———————————————————-

Sample Output 09

Enter First Number: hardwork

Sorry Invalid Input !!! Please enter Integer / Float  Number

Plan and Design Solution to the Task
Input-Processing-Output
  • Input
    • Data
      • An Integer Number
    • Instruction(s)
      • Make a Decision – Which Integer Number is Greater? 
  • Output
    • Display a Message (on the Output Screen) whether the Input Integer Number is Greater
  • Processing
    • Use Nested if Conditions for Decision Making – To check which the Integer Number is Greater?
    • Use print() Function  – To display the Message (on the Output Screen) which Integer Number is Greater?
Pseudo Code

Step 1: Start

Step 2: Input – number1 (Integer Value)

Step 3: Input – number2 (Integer Value)

Step 4: Input – number3 (Integer Value)

Step 5: if number1 > number2

                    if number1 > number3

                       print(“number1 is greater than number3”)

                    else:

                       print(“number1 is less than number3”)

              print(“number1 is greater than number2”)

              elif number2 > number3

                    if number2 > number1

                       print(“number2 is greater than number1”)

                     else:

                       print(“number2 is less than number1”)

              print(“number2 is greater than number3”)    

              elif number3 > number1

                    if number3 > number2

                       print(“number3 is greater than number2”)

                    else:

                       print(“number3 is less than number2”)

              print(“number3 is greater than number1”)

              else

                  print(“number1,number2 and number3 are equal”)

              endif

Step 6: Stop

Flow Chart
Implementation in Python
Code
				
					'''
__author__   = Ms. Samavi Salman
__copyright__= Copyright I 2020 Ms. Samavi Salman
__license__  = Public Domain
__version__  = 1.0
'''

'''
The main purpose of this Program is to take three Numbers as Input from User and check which number is Greater?
'''

try:
    # Take a Number as Input from User
    number1 = float(input("Enter First Number: "))
    number2 = float(input("Enter Second Number: "))
    number3 = float(input("Enter Third Number: "))

    # Decision Making - Check whether Condition is True or False 
    if number1 > number2:

        if number1 > number3:
            print("number1 is greater than number3")
        else:
            print("number1 is less than number3")

        print("number1 is greater than number2")

    # Decision Making - Check whether Condition is True or False 
    elif number2 > number3:

        if number2 > number1:
            print("number2 is greater than number1")
        else:
            print("number2 is less than number1")

        print("number2 is greater than number3")

    # Decision Making - Check whether Condition is True or False 
    elif number3 > number1:

        if number3 > number2:
            print("number3 is greater than number2")
        else:
            print("number3 is less than number2")

        print("number3 is greater than number1")
    
    else:
        print("number1,number2 and number3 are equal")

except ValueError:
    print("Sorry Invalid Input !!! Please enter Integer / Float  Number")
Execution of Code (Dry Run)
Python Statement
Calculations
Variable(s)
Output Screen

try:

   

number1 = float(input(“Enter First Number: “))

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

number2 = float(input(“Enter Second Number: “))

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

number3 = float(input(“Enter Third Number: “))

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

if number1 > number2:

Decision Making – Check Whether Condition is True or False 


number1 > number2

300 > 550

False (i.e., Statement(s) will be executed after if-Statement)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

if number1 > number3:

This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

print(“number1 is greater than number3”)

This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

else:

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

print(“number1 is less than number3”)

This Statement will not be executed because Condition is True in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

print(“number1 is greater than number2”)

This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

elif number2 > number3:

Decision Making – Check Whether Condition is True or False 


number2 > number3

550 > 120

True (i.e., Statement(s) will be executed after if-Statement)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

if number2 > number1:

Decision Making – Check Whether Condition is True or False 


number2 > number3

550 > 300

True (i.e., Statement(s) will be executed after if-Statement)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

print(“number2 is greater than number1”)

This Statement will be executed because Condition is True in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

else:

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

print(“number2 is less than number1”)

This Statement will not be executed because Condition is True in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

print(“number2 is greater than number3”)

This Statement will be executed because Condition is True in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

elif number3 > number1:

Decision Making – Check Whether Condition is True or False 


number3 > number1

120 > 300

False (i.e., Statement(s) will be executed after if-Statement)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

if number3 > number2:

This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

print(“number3 is greater than number2”)

This Statement will not be executed because Condition is True in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

else:

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

print(“number3 is less than number2”)

This Statement will be executed because Condition is False in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

print(“number3 is greater than number1”)

This Statement will not be executed because Condition is True in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

else:

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

print(“number1,number2 and number3 are equal”)

This Statement will not be executed because Condition is True in above if-Statement (see Output Screen)

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

except ValueError:

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

print(“Sorry Invalid Input !!! Please enter Integer Number”)

 

number1 = 300

number2 = 550

number3 = 120

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

Output of Code 

Enter First Integer Number: 300

Enter Second Integer Number: 550

Enter Third Integer Number: 120

number2 is greater than number1

number2 is greater than number3

 



Chapter 18 - if-elif Selection Structure
Chapter 20 - Repetition Structures in Python
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