3.7 Mastering Nested Conditionals - Unlocking Advanced Decision-Making in Programming

Introduction

Nested conditionals are a fundamental concept in programming where one conditional statement is placed inside another. This allows for more complex decision-making processes and enables programs to handle a wider range of scenarios.

Objectives

• Understand what nested conditionals are.
• Write pseudocode using nested conditionals.
• Apply nested conditionals to solve problems.

Key Concepts

• Conditional Statements: Used to perform different actions based on different conditions.
• Nested Conditionals: A conditional statement inside another conditional statement.

Example Syntax (College Board Pseudocode)

College Board pseudocode uses the following structure for conditional statements:

IF condition1
{
    // Code block for condition1
    IF condition2
    {
        // Code block for condition2
    }
    ELSE
    {
        // Code block if condition2 is false
    }
}
ELSE
{
    // Code block if condition1 is false
}


`Example 1: Checking Grade Categories`

## Pseudocode
Let's write a pseudocode to determine the grade category based on a score:


```python
IF score >= 90
{
    DISPLAY "A"
}
ELSE
{
    IF score >= 80
    {
        DISPLAY "B"
    }
    ELSE
    {
        IF score >= 70
        {
            DISPLAY "C"
        }
        ELSE
        {
            IF score >= 60
            {
                DISPLAY "D"
            }
            ELSE
            {
                DISPLAY "F"
            }
        }
    }
}

Python

Here is the equivalent Python code:

score = 85

if score >= 90:
    print("A")
else:
    if score >= 80:
        print("B")
    else:
        if score >= 70:
            print("C")
        else:
            if score >= 60:
                print("D")
            else:
                print("F")

B

Javascript

Here is the equivalent Javascript code example:

let score = 85;

if (score >= 90) {
    console.log("A");
} else if (score >= 80) {
    console.log("B");
} else if (score >= 70) {
    console.log("C");
} else if (score >= 60) {
    console.log("D");
} else {
    console.log("F");
}

Example 2: Determining Eligibility for a Loan

Pseudocode

Let’s consider a scenario where we determine if a person is eligible for a loan based on their credit score and income:

IF credit_score >= 700
{
    IF income >= 50000
    {
        DISPLAY "Eligible for loan"
    }
    ELSE
    {
        DISPLAY "Not eligible for loan due to low income"
    }
}
ELSE
{
    DISPLAY "Not eligible for loan due to low credit score"
}

Python

Here is the equivalent Python code:

credit_score = 750
income = 60000

if credit_score >= 700:
    if income >= 50000:
        print("Eligible for loan")
    else:
        print("Not eligible for loan due to low income")
else:
    print("Not eligible for loan due to low credit score")

Javascript

Here is the equivalent Javascript code:

let credit_score = 750;
let income = 60000;

if (credit_score >= 700) {
    if (income >= 50000) {
        console.log("Eligible for loan");
    } else {
        console.log("Not eligible for loan due to low income");
    }
} else {
    console.log("Not eligible for loan due to low credit score");
}

Example 3 Write pseudocode to determine if a person qualifies for a discount based on their membership status and purchase amount:

If the person is a member:

• If the purchase amount is greater than $100, they get a 20% discount.
• Otherwise, they get a 10% discount. If the person is not a member:
• If the purchase amount is greater than $100, they get a 5% discount. - Otherwise, they get no discount.

IF is_member = TRUE
{
    IF purchase_amount > 100
    {
        DISPLAY "20% discount"
    }
    ELSE
    {
        DISPLAY "10% discount"
    }
}
ELSE
{
    IF purchase_amount > 100
    {
        DISPLAY "5% discount"
    }
    ELSE
    {
        DISPLAY "No discount"
    }
}

Quiz!

Homework (Hacks)

• Write pseudocode to determine if a student passes a class based on their exam scores and attendance using nested conditionals.
• Write a python segment to decide the shipping cost based on the weight of a package and the delivery speed chosen (standard or express) using nested conditionals.
• Write a python segment to have different ticket prices for different ages, with a discount for students

Challenge Hack

Write a program that helps a user determine the type of triangle based on the lengths of its sides. The program should prompt the user to input three positive numbers representing the sides of a triangle. Your task is to use nested conditionals to check the following:

First, verify if the three sides can form a valid triangle (hint: the sum of any two sides must be greater than the third side). If it’s a valid triangle, further classify it into one of the following categories:

• Equilateral Triangle: All sides are equal.
• Isosceles Triangle: Two sides are equal.
• Scalene Triangle: No sides are equal. If the sides do not form a valid triangle, the program should display an appropriate message.

Requirements: Use nested conditionals to handle the logic for checking the type of triangle. Include input validation to ensure the user enters positive numbers.

Need Help?

Here’s some solutions.