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Conditional Statements in Python
course content

Course Content

Conditional Statements in Python

Conditional Statements in Python

1. Python if Statement
Introduction to if StatementSyntax of if StatementChallenge: MarioComparison OperatorsLogical OperatorsOperators Precendence
2. Python if-else Statement
Introduction to if-else StatementSyntax of if-else StatementChallenge: Geometric FigureChallenge: Rock, Paper and Scissors
3. Python if-elif-else Statement
Introduction to if-elif-else StatementChallenge: Car BrandsChallenge: Ordinal AdjectivesChallenge: Music Playlist Generator
4. Python Ternary Operator
Conditional ExpressionChallenge: Discount CalculatorChallenge: Password Strength

bookIntroduction to if-else Statement

Let's look at some examples first.

Example 1:

Checking a number for negativity.


              
12345

            
number = 15
if number >= 0:
    print('this number is positive:', number)
if number < 0:
    print('this number is negative', number)
copy

Example 2:

Checking whether a chocolate bar is expensive or has an average price.


              
12345

            
price_of_chocolate = 5
if price_of_chocolate <= 3:
    print('This a chocolate bar has an average price.')
if price_of_chocolate > 3:
    print('This a chocolate bar is expensive.')
copy

We can observe that to address various situations, it's necessary to write if-statements multiple times.

However, to adhere to the DRY ("Don't Repeat Yourself", one of the principles of good code) principle and maintain conciseness, we can make use of the else keyword.

Let's rewrite the example above and simplify them.

Example 3:


              
12345

            
number = 15
if number >= 0:
    print(f'Number {number} is positive.')
else:
    print(f'Number {number} is negative.')
copy

Example 4:


              
12345

            
price_of_chocolate = 5
if price_of_chocolate <= 3:
    print('This chocolate bar has an average price.')
else:
    print('This chocolate bar is expensive.')
copy

For a clearer understanding of the if-else expression's functionality, refer to the diagram below.

Time to consolidate your knowledge.

Task

Let's write a program that takes 3 numbers as input, these will be the sides of a triangle, and our program will check and say whether it is really possible to build a triangle from these three segments, or not.

Recall the conditions that the segments must satisfy in order to be able to construct a triangle :either side of an arbitrary triangle is less than the sum of its other two sides. x + y > z and x + z > y and y + z > x.

Example

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 2. Chapter 1
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bookIntroduction to if-else Statement

Let's look at some examples first.

Example 1:

Checking a number for negativity.


              
12345

            
number = 15
if number >= 0:
    print('this number is positive:', number)
if number < 0:
    print('this number is negative', number)
copy

Example 2:

Checking whether a chocolate bar is expensive or has an average price.


              
12345

            
price_of_chocolate = 5
if price_of_chocolate <= 3:
    print('This a chocolate bar has an average price.')
if price_of_chocolate > 3:
    print('This a chocolate bar is expensive.')
copy

We can observe that to address various situations, it's necessary to write if-statements multiple times.

However, to adhere to the DRY ("Don't Repeat Yourself", one of the principles of good code) principle and maintain conciseness, we can make use of the else keyword.

Let's rewrite the example above and simplify them.

Example 3:


              
12345

            
number = 15
if number >= 0:
    print(f'Number {number} is positive.')
else:
    print(f'Number {number} is negative.')
copy

Example 4:


              
12345

            
price_of_chocolate = 5
if price_of_chocolate <= 3:
    print('This chocolate bar has an average price.')
else:
    print('This chocolate bar is expensive.')
copy

For a clearer understanding of the if-else expression's functionality, refer to the diagram below.

Time to consolidate your knowledge.

Task

Let's write a program that takes 3 numbers as input, these will be the sides of a triangle, and our program will check and say whether it is really possible to build a triangle from these three segments, or not.

Recall the conditions that the segments must satisfy in order to be able to construct a triangle :either side of an arbitrary triangle is less than the sum of its other two sides. x + y > z and x + z > y and y + z > x.

Example

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 2. Chapter 1
toggle bottom row

bookIntroduction to if-else Statement

Let's look at some examples first.

Example 1:

Checking a number for negativity.


              
12345

            
number = 15
if number >= 0:
    print('this number is positive:', number)
if number < 0:
    print('this number is negative', number)
copy

Example 2:

Checking whether a chocolate bar is expensive or has an average price.


              
12345

            
price_of_chocolate = 5
if price_of_chocolate <= 3:
    print('This a chocolate bar has an average price.')
if price_of_chocolate > 3:
    print('This a chocolate bar is expensive.')
copy

We can observe that to address various situations, it's necessary to write if-statements multiple times.

However, to adhere to the DRY ("Don't Repeat Yourself", one of the principles of good code) principle and maintain conciseness, we can make use of the else keyword.

Let's rewrite the example above and simplify them.

Example 3:


              
12345

            
number = 15
if number >= 0:
    print(f'Number {number} is positive.')
else:
    print(f'Number {number} is negative.')
copy

Example 4:


              
12345

            
price_of_chocolate = 5
if price_of_chocolate <= 3:
    print('This chocolate bar has an average price.')
else:
    print('This chocolate bar is expensive.')
copy

For a clearer understanding of the if-else expression's functionality, refer to the diagram below.

Time to consolidate your knowledge.

Task

Let's write a program that takes 3 numbers as input, these will be the sides of a triangle, and our program will check and say whether it is really possible to build a triangle from these three segments, or not.

Recall the conditions that the segments must satisfy in order to be able to construct a triangle :either side of an arbitrary triangle is less than the sum of its other two sides. x + y > z and x + z > y and y + z > x.

Example

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Let's look at some examples first.

Example 1:

Checking a number for negativity.


              
12345

            
number = 15
if number >= 0:
    print('this number is positive:', number)
if number < 0:
    print('this number is negative', number)
copy

Example 2:

Checking whether a chocolate bar is expensive or has an average price.


              
12345

            
price_of_chocolate = 5
if price_of_chocolate <= 3:
    print('This a chocolate bar has an average price.')
if price_of_chocolate > 3:
    print('This a chocolate bar is expensive.')
copy

We can observe that to address various situations, it's necessary to write if-statements multiple times.

However, to adhere to the DRY ("Don't Repeat Yourself", one of the principles of good code) principle and maintain conciseness, we can make use of the else keyword.

Let's rewrite the example above and simplify them.

Example 3:


              
12345

            
number = 15
if number >= 0:
    print(f'Number {number} is positive.')
else:
    print(f'Number {number} is negative.')
copy

Example 4:


              
12345

            
price_of_chocolate = 5
if price_of_chocolate <= 3:
    print('This chocolate bar has an average price.')
else:
    print('This chocolate bar is expensive.')
copy

For a clearer understanding of the if-else expression's functionality, refer to the diagram below.

Time to consolidate your knowledge.

Task

Let's write a program that takes 3 numbers as input, these will be the sides of a triangle, and our program will check and say whether it is really possible to build a triangle from these three segments, or not.

Recall the conditions that the segments must satisfy in order to be able to construct a triangle :either side of an arbitrary triangle is less than the sum of its other two sides. x + y > z and x + z > y and y + z > x.

Example

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Section 2. Chapter 1
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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