Introduction to Python

September 25, 2022

Chapter 16 - if Selection Structure

IF Statement in Python

Definition
- if statement is an expression that can be evaluated as True or False and is called a conditional test
- It executes a set of statements conditionally, based on the value of a logical expression
Purpose
- The main purpose if statement is that it takes the form of an if test, followed by one or more optional elif (“else if”) tests and a final optional else block
  - Python if Statement is used for decision-making operations
Importance
- When the if statement runs, Python executes the block of code associated with the first test that evaluates to true, or the else block if all tests prove false
- Python uses the if keyword to implement decision control
Strengths
- If statement is used to satisfy the given condition(s) and then execute the particular set of code(s)
Weakness
- If statement checks all the conditions mentioned in a program which results in slow compilation and increases computational cost
Suitable to Use
- if statement to perform operations when there are multiple possibilities and each must be evaluated differently

Single if Statement

				
					'''
if Condition is True the block will be executed otherwise the control will move to the endif statement
'''

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

Note
- If Condition is True, then
  - Statements after if-Statement will be executed
- If Condition is False, then
  - Statements after if-Statement will not be executed
Conclusion
- In Decision Making
  - Some Statements will be executed and
  - Some statements will be skipped

Multiple if Statement

				
					'''
if Condition is True the block will be executed otherwise the control will move to the next if statement. If the condition is True, the block of if condition will be executed.
'''

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

Note
- If Condition is True, then
  - Statements after if-Statement will be executed
- If Condition is False, then
  - Statements after if-Statement will not be executed and the control will be moved to next if condition
Conclusion
- In Decision Making
  - Some Statements will be executed and
  - Some statements will be skipped

Completely and Correctly Understand a Task

Task Description

Two students are playing a game. One student rolled a dice and the other have to identify if the number rolled is even or odd. 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: 100

100 is an Even Number

——————————————————-

Sample Output 03

Enter an Integer Number: 10.25

Sorry Invalid Input!!! Please Enter an Integer Number

——————————————————-

Sample Output 04

Enter an Integer Number: honest

Sorry Invalid Input!!! Please Enter an 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 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

endif

if Modulus of number with 2 is equal to 1

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 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
    if number % 2 == 1:
        print(number, "is an Odd Number")
except ValueError:
    print("Sorry Invalid Input!!! Please Enter an Integer Number")

Execution of Code (Dry Run)
Python Statement	Calculations	Variable(s)	Output Screen
try:
number = int(input(“Enter an Integer Number: “))		number = 5	Enter an Integer Number: 5
if number % 2 == 0:	Decision Making – Check Whether Condition is True or False number % 2 == 0 5 % 2 == 0 1 == 0 False (i.e., Statement(s) will be executed after if-Statement)	number = 5	Enter an Integer Number: 5
print(number, “is an Even Number”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number = 5	Enter an Integer Number: 5
if number % 2 == 1:	Decision Making – Check Whether Condition is True or False number % 2 == 0 5 % 2 == 1 1 == 1 True (i.e., Statement(s) will be executed after if-Statement)	number = 5	Enter an Integer Number: 5
print(number, “is an Odd Number”)	This Statement will be executed because Condition is True in above if-Statement (see Output Screen)	number = 5	Enter an Integer Number: 5 5 is an Odd Number
except:		number = 5	Enter an Integer Number: 5 5 is an Odd Number
print(“Sorry Invalid Input!!! Please Enter an Integer Number”)		number = 5	Enter an Integer Number: 5 5 is an Odd Number
Output of Code
Enter an Integer Number: 5 5 is an Odd Number

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 – if operator == ‘-‘
  - Condition for * Operator – if operator == ‘*’
  - Condition for / Operator – if operator == ‘/’
  - Condition for ** Operator – if 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 is equal to ‘+’

Print – Sum of number1 and number2

endif

if operator is equal to ‘-‘

Print – Subtraction of number2 from number1

endif

if operator is equal to ‘*’

Print – Product (Multiplication) of number1 and number2

endif

if operator is equal to ‘/’

Print – Division of number1 by number2

endif

if operator is equal to ‘**’

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 (Integer / Float)  and an Operator as Input from User and perform Arithmetic Operation on Operands (Two Numbers) based on Value of Operator 
'''

try:
    # Take Two Numbers (Integer / 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)

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

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

    # Decision Making Check whether Value of Operator is / or not
    if operator == '/':
        print(number1,"/",number2,"=", number1 / number2)

    # Decision Making Check whether Value of Operator is ** or not
    if 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 (Dry Run)
Python Statement	Calculations	Variable(s)	Output Screen
try:
number1 = float(input(“Enter First Number: “))		number1 = 10	Enter First Number: 10
number2 = float(input(“Enter Second Number: “))		number1 = 10 number2 = 30	Enter First Number: 10 Enter Second Number: 30
operator = input(“Enter an Operator: “)		number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = /**	Enter First Number: 10 Enter Second Number: 30 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 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = /**	Enter First Number: 10 Enter Second Number: 30 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 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = /**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: /
if operator == ‘-‘:	Decision Making – Check Whether Condition is True or False / == – False (i.e., Statement(s) will be executed after if-Statement)	number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = /**	Enter First Number: 10 Enter Second Number: 30 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 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = /**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: /
*if operator == ‘’:**	Decision Making – Check Whether Condition is True or False / == * False (i.e., Statement(s) will be executed after if-Statement)	number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = /**	Enter First Number: 10 Enter Second Number: 30 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 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = /**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: /
if operator == ‘/’:	Decision Making – Check Whether Condition is True or False / == / True (i.e., Statement(s) will be executed after if-Statement)	number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = /**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: /
print(number1,”/”,number2,”=”, number1 / number2)	10 / 30 = 0.33 This Statement will be executed because Condition is True in above if-Statement (see Output Screen)	number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = / 10 / 30 = 0.33**	Enter First Integer Number: 10 Enter Second Integer Number: 30 Enter an Integer Number: / Calculate Division of Numbers 10 30 10 / 30 = 0.33
if operator == ‘’:**	Decision Making – Check Whether Condition is True or False / == False (i.e., Statement(s) will be executed after if-Statement)**	number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = / 10 / 30 = 0.33**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: / 10 / 30 = 0.33
print(number1,””,number2,”=”, number1 number2)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = / 10 / 30 = 0.33**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: / 10 / 30 = 0.33
except ValueError:		number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = / 10 / 30 = 0.33**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: / 10 / 30 = 0.33
print(“Sorry Invalid Input. Please enter Integer / Float Number”)		number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = / 10 / 30 = 0.33**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: / 10 / 30 = 0.33
except ZeroDivisionError:		number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = / 10 / 30 = 0.33**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: / 10 / 30 = 0.33
print(“Sorry Invalid Division. Please enter Integer Number other than ZERO”)		number1 = 10 number2 = 30 *operators = ‘+’, ‘-‘, ‘’, ‘/’ operator = / 10 / 30 = 0.33**	Enter First Number: 10 Enter Second Number: 30 Enter an Operator: / 10 / 30 = 0.33
Output of Code
Enter First Number: 10 Enter Second Number: 30 Enter an Operator: / 10 / 30 = 0.33

Completely and Correctly Understand a Task

Task Description

A Teacher is comparing marks of Students in two quizzes. 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 tan 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 whether number1 is greater than number2, number2 is greater than number1 or both numbers are equal

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

endif

if number2 is greater than number2

Print – number2 is greater than number1

endif

if 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 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")

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

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

Completely and Correctly Understand a Task

Task Description

A Teacher wants to mark the status of Students as Pass or Fail. Write a Python Program which takes Marks of a Student in a Course as Input (from User) and makes a decision: (1) Student Passed the Course (2) Student Failed in the Course?

Sample Outputs

Sample Output 01

Enter Marks in Course: 89.5

You Passed the Course of Introduction to Python

————————————————————–

Sample Output 02

Enter Marks in Course: 49.9

You Failed the Course of Introduction to Python

————————————————————–

Sample Output 03

Enter Marks in Course: 50

You Passed the Course of Introduction to Python

————————————————————–

Sample Output 04

Enter Marks in Course: 45

You Failed the Course of Introduction to Python

————————————————————–

Sample Output 05

Enter Marks in Course: passion

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

Plan and Design Solution to the Task

Input-Processing-Output

Input
- Data
  - Marks (of a Student in a Course)
- Instruction(s)
  - Make a Decision – Whether the Student Passed the Course or Not?
Output
- Display a Message (on the Output Screen) whether the Student passed the Course or not?
Processing
- Use Conditions for Decision Making – To check whether the Student passed / failed the Course
  - Condition 01 (To Check Whether Student Passed the Course) – marks >= 50.0
  - Condition 02 (To Check Whether Student Failed the Course) – marks < 50.0
  - Use print() Function – To display the Message (on the Output Screen) whether the Student passed/ failed the Course

Pseudo Code

Step 1: Start

Step 2: Input – number (Integer Value)

Step 3: if marks are greater than or equal to 50.0

Print – You Passed the Course

endif

if marks are less than 50.0

Print – You Failed the Course

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 Marks in Introduction to Python course as Input from User and check whether the Student Passed the Course or Not
'''

try:
    # Take a Marks (Integer / Float) as Input from User
    marks = float(input("Enter Marks in Course: "))

    # Decision Making - Check whether Condition is True or False
    if marks >= 50.0:
        print("You Passed the Course of Introduction to Python")

    if marks < 50:
        print("You Failed the Course of Introduction to Python")

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

Execution of Code (Dry Run)
Python Statement	Calculations	Variable(s)	Output Screen
try:
marks = float(input(“Enter Marks in Course: “))		marks = 49.99	Enter Marks in Course: 49.99
if marks >= 50.0:	Decision Making – Check Whether Condition is True or False marks >= 50.0 49.99 >= 50.0 False (i.e., Statement(s) will be executed after if-Statement)	marks = 49.99	Enter Marks in Course: 49.99
print(“You Passed the Course of Introduction to Python”)	This Statement will not be executed because Condition is False in above if-Statement (see Output Screen)	marks = 49.99	Enter Marks in Course: 60
if marks < 50.0:	Decision Making – Check Whether Condition is True or False marks < 50.0 49.99 < 50.0 True (i.e., Statement(s) will be executed after if-Statement)	marks = 49.99	Enter Marks in Course: 49.99
print(“You Failed the Course of Introduction to Python”)	This Statement will be executed because Condition is True in above if-Statement (see Output Screen)	marks = 49.99	Enter Marks in Course: 49.99 You Failed the Course of Introduction to Python
except ValueError:		marks = 49.99	Enter Marks in Course: 49.99 You Failed the Course of Introduction to Python
print(“Sorry !!!. Invalid Input. Please enter Integer / Float Number”)		marks = 49.99	Enter Marks in Course: 49.99 You Failed the Course of Introduction to Python
Output of Code
Enter Marks in Course: 49.99 You Failed the Course of Introduction to Python

Completely and Correctly Understand a Task

Task Description

Calculate the Weather Forecast for today. Write a Python Program which takes a Number as Input (from User) and makes a decision: (1) Number is Positive (2) Number is Negative?

Sample Outputs

Sample Output 01

Enter a Number: 50.45

50.45 is a Positive Number

————————————————

Sample Output 02

Enter a Number: 0

0 is a Positive Number

————————————————

Sample Output 03

Enter a Number: -45.76

-45.76 is a Negative Number

————————————————

Sample Output 04

Enter a Number: -1000

-1000 is a Negative Number

————————————————

Sample Output 05

Enter a Number: courage

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

Plan and Design Solution to the Task

Input-Processing-Output

Input
- Data
  - A Number
- Instruction(s)
  - Make a Decision – Whether the Number is Positive or Negative?
Output
- Display a Message (on the Output Screen) whether the Number is Positive or Negative?
Processing
- Use if Selection Structure for Decision Making – To check whether the Number is Positive or Negative?
  - Condition (To Check Whether the Number is Positive – number >= 0.0
  - Condition (To Check Whether the Number is Negative) – number < 0.0
  - Use print() Function – To display the Message (on the Output Screen) whether the Number is Positive or Negative?

Pseudo Code

Step 1: Start

Step 2: Input – number

Step 3: if number is greater than or equal to 0.0

Print – Positive Number

endif

if number is less than 0.0

Print – Negative 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 a Number (Integer / Float) as Input from User and check whether it’s a Positive Number or a Negative Number?
'''

try:
    # Take a Number (Integer / Float) as Input from User
    number = float(input("Enter a Number: "))

    # Decision Making - Check whether Condition is True or False 
    if number >= 0.0:
        print(number, "is a Positive Number")
    if number < 0.0:
        print(number, "is a Negative Number")

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

Execution of Code (Dry Run)
Python Statement	Calculations	Variable(s)	Output Screen
number = int(input(“Enter an Integer Number: “))		number = -100	Enter 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) will be executed after if-Statement)	number = -100	Enter 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 = -100	Enter an Integer Number: -100
if number < 0.0:	Decision Making – Check Whether Condition is True or False number < 0.0 -100 < 0.0 True (i.e., Statement(s) will be executed after if-Statement)	number = -100	Enter 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

TODO and Your Turn

Todo Tasks

Your Turn Tasks

Todo Tasks

Your Turn Tasks

Ilm o Irfan

Introduction to Python

Table of Contents

Chapter 16 - if Selection Structure

IF Statement in Python

Single if Statement

Multiple if Statement

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

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

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