Introduction to Python

September 26, 2022

Chapter 18 - if-elif Selection Structure

IF - ELIF Statement in Python

Definition
- The elif is short for else if. It allows us to check for multiple expressions. If the condition for if is False, it checks the condition of the next elif block and so on. If all the conditions are False, the body of else is executed
Purpose
- The main purpose is that the elif condition is used to include multiple conditional expressions after the if condition or between the if and else conditions. The elif block is executed if the specified condition evaluates to True
Importance
- Use the elif condition is used to include multiple conditional expressions after the if condition or between the if and else conditions. The elif block is executed if the specified condition evaluates to True
Suitable to Use
- When there is more than one possibility of a condition to occur
- The elif statement allows you to check multiple expressions for TRUE and execute a block of code as soon as one of the conditions evaluates to TRUE.

				
					'''
if Condition is True the block will be executed otherwise the control will move to the elif statement and check the condition if condition is true statements inside the block will be executed otherwise next condition will be checked
'''

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>
elif condition:
    <statement(s)01>
    <statement(s)02>
    <statement(s)03>
    ….
    <statement(s)N>
endif

				
					'''
__author__ = Ms. Samavi Salman
__copyright__= Copyright I 2020 Ms. Samavi Salman
__license__ = Public Domain
__version__ = 1.0
'''

try:
    print("Before Multiple If-Statement") 
    operators = int(input("Enter an Arithmetic Operator"))
    if operators == '+':
        print("Condition 01 is True")
        print("Operator is +")
    elif operators == '-':
        print("Contrition 02 is True")
        print("Operator is -")
    print("After Multiple if-Statement")
except:
    print("Sorry Invalid Operator. Please enter a Valid Operator")

Execution of Code (Dry Run)
Python Statement	Calculations	Variable(s)	Output
try:
print(“Before Multiple If-Statement”)			Before Multiple If-Statement
operators = int(input(“Enter an Arithmetic Operator”))		operators = +	Before Multiple If-Statement Enter an Arithmetic Operator
if operators == ‘+’:	Decision Making – Check Whether Condition is True or False operators == ‘+’ + == + True (i.e., Statement(s) will be executed after if-Statement)	operators = +	Before Multiple If-Statement Enter an Arithmetic Operator
print(“Condition 01 is True”)	This Statement will be executed because Condition is True in above if-Statement (see Output Screen)	operators = +	Before Multiple If-Statement Enter an Arithmetic Operator
print(“Operator is +”)		operators = +	Before Multiple If-Statement Enter an Arithmetic Operator Operator is +
elif operators == ‘-‘:	Decision Making – Check Whether Condition is True or False operators == ‘-‘ + == – False (i.e., Statement(s) will be executed after if-Statement)	operators = +	Before Multiple If-Statement Enter an Arithmetic Operator Operator is +
print(“Contrition 02 is True”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	operators = +	Before Multiple If-Statement Enter an Arithmetic Operator Operator is +
print(“Operator is -“)		operators = +	Before Multiple If-Statement Enter an Arithmetic Operator Operator is +
print(“After Multiple if-Statement”)		operators = +	Before Multiple If-Statement Enter an Arithmetic Operator Operator is + After Multiple if-Statement
except:		operators = +	Before Multiple If-Statement Enter an Arithmetic Operator Operator is + After Multiple if-Statement
print(“Sorry Invalid Operator. Please enter a Valid Operator”)		operators = +	Before Multiple If-Statement Enter an Arithmetic Operator Operator is + After Multiple if-Statement

				
					'''
__author__ = Ms. Samavi Salman
__copyright__= Copyright I 2020 Ms. Samavi Salman
__license__ = Public Domain
__version__ = 1.0
'''

try:
    print("Before Multiple If-Statement") 
    number1 = int(input("Enter First Integer Number"))
    number2 = int(input("Enter Second Integer Number "))
    if number1 == number2:
        print("number1 is equal to number2")
    elif number1 < number2:
        print("number1 is less than number2")
    elif number1 > number2:
        print("number1 is greater than number2")
    print("After Multiple if-Statement")
except:
    print("Sorry Invalid Operator. Please enter a Valid Operator")

Execution of Code (Dry Run)
Python Statement	Calculations	Variable(s)	Output
try:
print(“Before Multiple If-Statement”)			Before Multiple If-Statement
number1 = int(input(“Enter First Integer Number”))		number1 = 230	Before Multiple If-Statement Enter First Integer Number 230
number2 = int(input(“Enter Second Integer Number”))		number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333
if number1 == number2:	Decision Making – Check Whether Condition is True or False number1 == number2 230 == 333 False (i.e., Statement(s) will be executed after if-Statement)	number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333
print(“number1 is equal to number2”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333
elif number1 < number2:	Decision Making – Check Whether Condition is True or False number1 < number2 230 < 333 True (i.e., Statement(s) will be executed after if-Statement)	number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333
print(“number1 is less than number2”)	This Statement will be executed because Condition is True in above if-Statement (see Output Screen)	number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333 number1 is less than number2
elif number1 > number2:	Decision Making – Check Whether Condition is True or False number1 > number2 230 > 333 False (i.e., Statement(s) will be executed after if-Statement)	number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333 number1 is less than number2
print(“number1 is greater than number2”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333 number1 is less than number2
print(“After Multiple if-Statement”)		number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333 number1 is less than number2 After Multiple if-Statement
except:		number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333 number1 is less than number2 After Multiple if-Statement
print(“Sorry Invalid Operator. Please enter a Valid Operator”)		number1 = 230 number2 = 333	Before Multiple If-Statement Enter First Integer Number 230 Enter Second Integer Number 333 number1 is less than number2 After Multiple if-Statement

				
					'''
__author__ = Ms. Samavi Salman
__copyright__= Copyright I 2020 Ms. Samavi Salman
__license__ = Public Domain
__version__ = 1.0
'''

try:
    print("Before Multiple If-Statement") 
    number = int(input("Enter a Number"))
    if number % 2 == 0:
        print(number, "is divisible by 2")
    elif number % 3 == 0:
        print(number, "is divisible by 3")
    elif number % 5 == 0:
        print(number, "is divisible by 5")
    print("After Multiple if-Statement")
except:
    print("Sorry Invalid Operator. Please enter a Valid Operator")

Execution of Code (Dry Run)
Python Statement	Calculations	Variable(s)	Output
try:
print(“Before Multiple If-Statement”)			Before Multiple If-Statement
number = int(input(“Enter a Number”))		number = 45	Before Multiple If-Statement
if number % 2 == 0:	Decision Making – Check Whether Condition is True or False number % 2 == 0 45 % 2 == 0 False (i.e., Statement(s) will be executed after if-Statement)	number = 45	Before Multiple If-Statement
print(number, “is divisible by 2”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number = 45	Before Multiple If-Statement
elif number % 3 == 0:	Decision Making – Check Whether Condition is True or False number % 3 == 0 45 % 3 == 0 True (i.e., Statement(s) will be executed after if-Statement)	number = 45	Before Multiple If-Statement 45 is divisible by 3
print(number, “is divisible by 3”)	This Statement will be executed because Condition is True in above if-Statement (see Output Screen)	number = 45	Before Multiple If-Statement 45 is divisible by 3
elif number % 5 == 0:	Decision Making – Check Whether Condition is True or False number % 5 == 0 45 % 5 == 0 True (i.e., Statement(s) will be executed after if-Statement)	number = 45	Before Multiple If-Statement 45 is divisible by 3
print(number, “is divisible by 5”)	This Statement will be executed because Condition is True in above if-Statement (see Output Screen)	number = 45	Before Multiple If-Statement 45 is divisible by 3
print(“After Multiple if-Statement”)		number = 45	Before Multiple If-Statement 45 is divisible by 3 After Multiple if-Statement
except:		number = 45	Before Multiple If-Statement 45 is divisible by 3 After Multiple if-Statement
print(“Sorry Invalid Operator. Please enter a Valid Operator”)		number = 45	Before Multiple If-Statement 45 is divisible by 3 After Multiple if-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 an Even Number or an Odd Number?

Sample Outputs

Sample Output 01 Enter an Integer Number: 5 5 is an Odd Number ————————————– Sample Output 02 Enter an Integer Number: 12 12 is an Odd Number ————————————– Sample Output 03 Enter an Integer Number: 500 500 is an Even 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 Odd or Even?
Output
- Display a Message (on the Output Screen) whether the Input Integer Number is an Even Number or Odd Number
Processing
- Use Conditions for Decision Making – To check whether the Integer Number is Odd or Even?
  - Condition for Even Number – number % 2 == 0
  - Condition for Odd Number – number % 2 == 1
  - Use print() Function – To display the Message (on the Output Screen) whether the Integer Number is Even or Odd?

Pseudo Code

Step 1: Start Step 2: Input – number (Integer Value) Step 3: if Modulus of number with 2 is equal to 0 Print – Even Number Step 5: elif Modulus of number with 2 is equal to 1 Print – Odd Number 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 an Integer Number as Input from User and check whether it’s an Even Number or an Odd 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 % 2 == 0:
        print(number, "is an Even Number")

    # Decision Making - Check whether Condition is True or False 
    elif number % 2 == 1:
        print(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
number = int(input(“Enter an Integer Number: “))		number = 6	Enter an Integer Number: 6
if number % 2 == 0:	Decision Making – Check Whether Condition is True or False number % 2 == 0 6 % 2 == 0 0 == 0 True (i.e., Statement(s) after if-Statement will be executed)	number = 6	Enter an Integer Number: 6
print(number, “is an Even Number”)	This Statement will be executed because Condition is True in above elif-Statement (see Output Screen)	number = 6	Enter an Integer Number: 6
elif number % 2 == 1:	Decision Making – Check Whether Condition is True or False number % 2 == 1 6 % 2 == 1 0 == 1 False (i.e., Statement(s) after elif-Statement will not be executed)	number = 6	Enter an Integer Number: 6
print(number, “is an Odd Number”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	number = 6	Enter an Integer Number:6 6 is an Even Number
Output of Code
Enter an Integer Number: 6 6 is an Even Number

Completely and Correctly Understand a Task

Task Description

Write a Python Program which takes two Integer Numbers as Input (from User) and makes a decision which Number is Greater?

Sample Outputs

Sample Output 01

Enter First Integer Number: 10

Enter Second Integer Number: 5

number1 is greater than number2

—————————————————–

Sample Output 02

Enter First Integer Number: 10

Enter Second Integer Number: 50

number1 is less than number2

Plan and Design Solution to the Task

Input-Processing-Output

Input

- Data

- - An Integer Number
- Instruction(s)
  - Make a Decision – Which number is greater?
Output
- Display a Message (on the Output Screen) which Input Integer Number is Greater
Processing
- Use Conditions for Decision Making – To check which Integer Number is Greater?
  - Condition for Greater Number (number1) – number1 > number2
  - Condition for Greater Number (number2) – number2 > number1
  - Use print() Function – To display the Message (on the Output Screen) which number is Greater?

Pseudo Code

Step 1: Start

Step 2: Input – number1 (Integer Value)

Step 3: Input – number2 (Integer Value)

Step 3: if number1 is greater than number2

Print – number1 is greater than number2

Step 5: elif number1 is less than number2

Print – number1 is less than number2

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 two Integer Numbers as Input from User and check which number is Greater?
'''

try:
    # Take an Integer Number as Input from User

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

    # Decision Making - Check whether Condition is True or False 
    if number1 > number2:
        print("number1 is greater than number2")
    elif number2 > number1:
        print("number2 is greater than number1")

    elif number1 == number2:
        print("number1 is equal to number2")

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

Execution of Code (Dry Run)
Python Statement	Calculations	Variable(s)	Output Screen
number1 = int(input(“Enter First Integer Number: “))		number1 = 10	Enter First Integer Number: 5
number2 = int(input(“Enter Second Integer Number: “))		number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10
if number1 > number2:	Decision Making – Check Whether Condition is True or False 10 > 5 True (i.e., Statement(s) after if-Statement will be executed)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10
print(“number1 is greater than number2”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10
elif number1 < number2:	Decision Making – Check Whether Condition is True or False 10 < 5 False (i.e., Statement(s) after elif-Statement will not be executed)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10
print(“number1 is less than number2”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10 number1 is less than number2
elif number1 == number2:	Decision Making – Check Whether Condition is True or False 10 == 5 False (i.e., Statement(s) after elif-Statement will not be executed)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10 number1 is less than number2
print(“number1 is equal to number2”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10 number1 is less than number2
Output of Code
Enter First Integer Number: 10 Enter Second Integer Number: 5 number1 is greater than number2

Completely and Correctly Understand a Task

Task Description

Write a Python Program which takes Marks of Student as Input (from User) and makes a decision whether the Student passes or fails the course of Introduction to Python?

Sample Outputs

Sample Output 01

Enter marks in Introduction to Python course: 60

Congratulations!!! You passed the course

——————————————–

Sample Output 02

Enter marks in Introduction to Python course: 49

Sorry!!! You failed the course

——————————————–

Sample Output 03

Enter marks in Introduction to Python course: 49.99

Unfortunately!!! You failed the course

Plan and Design Solution to the Task

Input-Processing-Output

Input

- Data

- - Marks (Integer or Float)
- Instruction(s)
  - Take Marks (marks) as input from the Student
  - Make a Decision – Whether the grade of Student is A, A-, B+, B, B-, C, C-, D, F?
Output
- Display a Message (on the Output Screen) whether the Student passes the Course of Introduction to Python or not
Processing
- Use Conditions for Decision Making – To check whether the Student passes the Course of Introduction to Python or not
  - Condition for A – marks >= 90
  - Condition for A- – 85 <= marks <= 89
  - Condition for B+ – 80 <= marks <= 84
  - Condition for B – 75 <= marks <= 79
  - Condition for B- – 70 <= marks <= 74
  - Condition for C+ – 65 <= marks <= 69
  - Condition for C – 60 <= marks <= 64
  - Condition for C- – 55 <= marks <= 59
  - Condition for D – 50 <= marks <= 54
  - Condition for F – marks <= 50
  - Use print() Function – To display the Message (on the Output Screen) whether the Student passes the Course of Introduction to Python?

Pseudo Code

Step 1: Start

Step 2: Input – number (Integer Value)

Step 3: if marks >= 90

Print – A Grade

Step 4: elif 85 <= marks <= 89

Print – A- Grade

Step 5: elif 80 <= marks <= 84

Print – B+ Grade

Step 6: elif 75 <= marks <= 79

Print – B Grade

Step 7: elif 70 <= marks <= 74

Print – B- Grade

Step 8: elif 65 <= marks <= 69

Print – C+ Grade

Step 9: elif 60 <= marks <= 64

Print – C Grade

Step 10: elif 55 <= marks <= 59

Print – C- Grade

Step 11: elif 50 <= marks <= 54

Print – D Grade

Step 12: elif marks <= 50

Print – F Grade

endif

Step 13: 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 an Even Number or an Odd Number?
'''

try:
    # Take an Integer Number as Input from User

    marks = float(input("Enter Marks in Course: "))

    # Decision Making - Check whether Condition is True or False 
    if marks >= 90:
        print("A Grade")

    elif 85 <= marks <= 89:
        print("A- Grade")

    elif 80 <= marks <= 84:
        print("B+ Grade")

    elif 75 <= marks <= 79:
        print("B Grade")

    elif 70 <= marks <= 74:
        print("B- Grade")

    elif 65 <= marks <= 69:
        print("C+ Grade")

    elif 60 <= marks <= 64:
        print("C Grade")

    elif 55 <= marks <= 59:
        print("C- Grade")

    elif 50 <= marks <= 54:
        print("D Grade")

    elif marks <= 50:
        print("F Grade")

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

Execution of Code (Dry Run)
Python Statement	Calculations	Variable(s)	Output Screen
marks = float(input(“Enter Marks in Course: “))		marks = 49.9	Enter Marks in Course: 49.9
if marks >= 90:	Decision Making – Check Whether Condition is True or False marks >= 90 49.9 >= 90 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“A Grade”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif 85 <= marks <= 89:	Decision Making – Check Whether Condition is True or False 85 <= marks <= 89 85 <= 49.9 <= 89 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“A- Grade”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif 80 <= marks <= 84:	Decision Making – Check Whether Condition is True or False 80 <= marks <= 84 80 <= 49.9 <= 84 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“B+ Grade”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif 75 <= marks <= 79:	Decision Making – Check Whether Condition is True or False 75 <= marks <= 79 75 <= 49.9 <= 79 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“B Grade”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif 70 <= marks <= 74:	Decision Making – Check Whether Condition is True or False 70 <= marks <= 74 70 <= 49.9 <= 74 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“B- Grade”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif 65 <= marks <= 69:	Decision Making – Check Whether Condition is True or False 65 <= marks <= 69 65 <= 49.9 <= 69 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“C+ Grade”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif 60 <= marks <= 64:	Decision Making – Check Whether Condition is True or False 60 <= marks <= 64 60 <= 49.9 <= 64 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“C Grade”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif 55 <= marks <= 59:	Decision Making – Check Whether Condition is True or False 55 <= marks <= 59 55 <= 49.9 <= 59 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“C- Grade”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif 50 <= marks <= 54:	Decision Making – Check Whether Condition is True or False 50 <= marks <= 54 50 <= 49.9 <= 54 False (i.e., Statement(s) after if-Statement will not be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“D Grade”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9
elif marks <= 50:	Decision Making – Check Whether Condition is True or False marks <= 50 49.9 <= 50 True (i.e., Statement(s) after if-Statement will be executed)	marks = 49.9	Enter Marks in Course: 49.9
print(“F Grade”)	This Statement will be executed because Condition is True in above elif-Statement (see Output Screen)	marks = 49.9	Enter Marks in Course: 49.9 F Grade
Output of Code
Enter Marks in Course: 49.9 F Grade

Completely and Correctly Understand a Task

Task Description

There are some balls of different color placed in two different boxes. Write a Python Program which takes two Numbers as Input (from User) and makes a decision: (1) First Number is greater than the Second Number, (2) Second Number is greater than First Number, or (3) Both Numbers are equal?

Sample Outputs

Sample Output 01

Enter First Number: 2000

Enter Second Number: 1000

number1 is greater than number2

———————————————————–

Sample Output 02

Enter First Number: 4000

Enter Second Number: 6000

number2 is greater than number1

———————————————————–

Sample Output 03

Enter First Number: 60.90

Enter Second Number: 60.90

number1 is equal to number2

———————————————————–

Sample Output 04

Enter First Number: loyal

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

———————————————————–

Sample Output 05

Enter First Number: 60

Enter Second Number: loyal

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

Plan and Design Solution to the Task

Input-Processing-Output

Input
- Data
  - Number 01
  - Number 02
- Instruction(s)
  - Make a Decision
    - First Number is Greater than the Second Number
    - Second Number is Greater than First Number
    - Both Numbers are Equal
Output
- Display a Message (on the Output Screen) based on Outcome of Decision
  - number1 is Greater than number2
  - number2 is Greater than number1
  - number1 is Equal to number2
Processing
- Use Conditions for Decision Making
  - Condition 01 (To Check Whether First Number is Greater Than Second Number) – number1 > number2
  - Condition 02 (To Check Whether Second Number is Greater Than First Number) – number2 > number1
  - Condition 03 (To Check Whether First Number is Equal to Second Number) – number1 == number2
  - Use print() Function – To display the Message on the Output Screen

Pseudo Code

Step 1: Start

Step 2: Input – number1 (Integer / Float Value)

Step 3: Input – number2 (Integer / Float Value)

Step 3: if number1 is greater than number2

Print – number1 is greater than number2

elif number2 is greater than number2

Print – number2 is greater than number1

elif number1 is equal to number2

Print – number1 is equal to number2

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 two Numbers (Integer / Float) as Input from User and check which number1 is Greater than number2 or vice versa
or both numbers are Equal?
'''

try:
    # Take two Numbers (Integer / Float) as Input from User

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

    # Decision Making - Check whether Condition is True or False
    if number1 > number2:
        print("number1 is greater than number2")

    elif number2 > number1:
        print("number2 is greater than number1")

    elif number1 == number2:
        print("number1 is equal to number2")

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 = int(input(“Enter First Integer Number: “))		number1 = 10	Enter First Integer Number: 5
number2 = int(input(“Enter Second Integer Number: “))		number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10
if number1 > number2:	Decision Making – Check Whether Condition is True or False 5 > 10 False (i.e., Statement(s) will be executed after if-Statement)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10
print(“number1 is greater than number2”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10
elif number2 > number1:	Decision Making – Check Whether Condition is True or False 10 > 5 True (i.e., Statement(s) will be executed after elif-Statement)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10
print(“number2 is greater than number1”)	This Statement will be executed because Condition is True in above elif-Statement (see Output Screen)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10 number2 is greater than number1
elif number1 == number2:	Decision Making – Check Whether Condition is True or False 10 == 5 False (i.e., Statement(s) will be executed after elif-Statement)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10 number1 is less than number2
print(“number1 is equal to number2”)	This Statement will not be executed because Condition is False in above elif-Statement (see Output Screen)	number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10 number1 is less than number2
except ValueError:		number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10 number1 is less than number2
print(“Sorry Invalid Input !!! Please enter Integer / Float Number”)		number1 = 10 number2 = 5	Enter First Integer Number: 5 Enter Second Integer Number: 10 number1 is less than number2
Output of Code
Enter First Integer Number: 10 Enter Second Integer Number: 5 number1 is greater than number2

Completely and Correctly Understand a Task

Task Description

Ms. Samavi buys some grocery and wants to calculate the price paid by her to the salesman and the change return by him. 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: 10

Enter Second Number: 20

Enter an Operator: +

10 + 20 = 30

——————————————

Sample Output 02

Enter First Number: 10

Enter Second Number: 20

Enter an Operator: –

10 – 20 = -10

——————————————

Sample Output 03

Enter First Number: 10

Enter Second Number: 20

Enter an Operator: *

10 * 20 = 200

——————————————

Sample Output 04

Enter First Number: 10

Enter Second Number: 20

Enter an Operator: /

10 / 20 = 0

——————————————

Sample Output 05

Enter First Number: 5

Enter Second Number: 2

Enter an Operator: **

5 ** 2 = 25

——————————————

Sample Output 06

Enter First Number: 10.25

Enter Second Number: 20.50

Enter an Operator: +

10.25 + 20.50 = 30.37

——————————————

Sample Output 07

Enter First Number: 10.25

Enter Second Number: 20.50

Enter an Operator: –

10.25 – 20.50 = -10.25

——————————————

Sample Output 08

Enter First Number: 10.25

Enter Second Number: 20.50

Enter an Operator: *

10.25 * 20.50 = 210.12

——————————————

Sample Output 09

Enter First Number: 10.25

Enter Second Number: 20.50

Enter an Operator: /

10.25 / 20.50 = 0.5

——————————————

Sample Output 10

Enter First Number: 10

Enter Second Number: 0

Enter an Operator: /

Sorry Invalid Division. Please enter Integer / Float Number other than ZERO

——————————————

Sample Output 11

Enter First Number: faith

Sorry Invalid Input. Please enter Integer / Float Number

——————————————

Sample Output 12

Enter First Number: 10

Enter Second Number: faith

Sorry Invalid Input. Please enter Integer / Float Number

——————————————

Sample Output 13

Enter First Number: 10

Enter Second Number: 20

Enter an Operator: #

Sorry Invalid Input. Please enter a Valid Operator

Plan and Design Solution to the Task

Input-Processing-Output

Input

- Data

- - Two Numbers
  - An Operator (+, -, *, /, **)
- Instruction(s)
  - Take Two Numbers as Input from 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

elif operator == ‘-‘

Print – Subtraction of number2 from number1

elif operator == ‘*’

Print – Product (Multiplication) of number1 and number2

elif operator == ‘/’

Print – Division of number1 by number2

elif operator == ‘**’

Print – Exponent of number1 with number2

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 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,"=", number1 ** number2)

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

except ZeroDivisionError:
    print("Sorry !!!. Invalid Division. Please enter Integer / Float Number other than ZERO")

Execution of Code
Python Statement	Calculations	Variable(s)	Output Screen
try:
number1 = float(input(“Enter First Number: “))		number1 = 5	Enter 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) will be executed after if-Statement)**	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) will be executed after if-Statement)**	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) will be executed after if-Statement)	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) will be executed after if-Statement)**	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 after if-Statement)	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
except ValueError:
print(“Sorry !!!. Invalid Input. Please enter Integer / Float Number”)
except ZeroDivisionError:
print(“Sorry !!!. Invalid Division. Please enter Integer / Float Number other than ZERO”)
Output of Code
Enter First Number: 10 Enter Second Number: 30 Enter an Operator: / 10 / 30 = 0.33

TODO and Your Turn

Todo Tasks

Your Turn Tasks

Todo Tasks

Your Turn Tasks

Ilm o Irfan

Introduction to Python

Table of Contents

Chapter 18 - if-elif Selection Structure

IF - ELIF Statement in Python

Execution of Code (Dry Run)

Python Statement

Calculations

Variable(s)

Output

Execution of Code (Dry Run)

Python Statement

Calculations

Variable(s)

Output

Execution of Code (Dry Run)

Python Statement

Calculations

Variable(s)

Output

Completely and Correctly Understand a Task

Task Description

Sample Outputs

Plan and Design Solution to the Task

Input-Processing-Output

Pseudo Code

Flow Chart

Implementation in Python

Code

Execution of Code (Dry Run)

Python Statement

Calculations

Variable(s)

Output Screen

Output of Code

Completely and Correctly Understand a Task

Task Description

Sample Outputs

Plan and Design Solution to the Task

Input-Processing-Output

Pseudo Code

Flow Chart

Implementation in Python

Code

Execution of Code (Dry Run)

Python Statement

Calculations

Variable(s)

Output Screen

Output of Code

Completely and Correctly Understand a Task

Task Description

Sample Outputs

Plan and Design Solution to the Task

Input-Processing-Output

Pseudo Code

Flow Chart

Implementation in Python

Code

Execution of Code (Dry Run)

Python Statement

Calculations

Variable(s)

Output Screen

Completely and Correctly Understand a Task

Task Description

Sample Outputs

Plan and Design Solution to the Task

Input-Processing-Output

Pseudo Code

Flow Chart

Implementation in Python

Code

Execution of Code (Dry Run)

Python Statement

Calculations

Variable(s)

Output Screen

Output of Code

Completely and Correctly Understand a Task