Relational operators in C++ - Mini Project: Build & Apply

Relational Operators Practice

📖 Scenario: You are helping a store manager compare product prices to decide which items are cheaper or more expensive.

🎯 Goal: Build a simple C++ program that uses relational operators to compare two product prices and shows the comparison results.

📋 What You'll Learn

Create two variables to store product prices

Create a variable to hold a threshold price

Use relational operators to compare prices with each other and with the threshold

Print the results of the comparisons

💡 Why This Matters

🌍 Real World

Comparing prices helps shoppers and store managers decide which products are cheaper or more expensive.

💼 Career

Understanding relational operators is essential for decision-making logic in programming jobs like software development and data analysis.

1

Create product price variables

Create two double variables called price1 and price2 with values 19.99 and 24.99 respectively.

C++

#include 

int main() {
    // Create price1 and price2 variables
    // Your code here

    return 0;
}

Hint

Use double type for prices and assign the exact values.

2

Add a threshold price variable

Create a double variable called threshold and set it to 20.00.

C++

#include 

int main() {
    double price1 = 19.99;
    double price2 = 24.99;
    // Create threshold variable
    // Your code here

    return 0;
}

Hint

Use double type and assign the exact value 20.00.

3

Compare prices using relational operators

Use relational operators to create four bool variables: isPrice1Less for price1 < price2, isPrice2Greater for price2 > price1, isPrice1BelowThreshold for price1 < threshold, and isPrice2AboveThreshold for price2 > threshold.

C++

#include 

int main() {
    double price1 = 19.99;
    double price2 = 24.99;
    double threshold = 20.00;
    // Create bool variables using relational operators
    // Your code here

    return 0;
}

Hint

Use < and > operators to compare the variables exactly as named.

4

Print the comparison results

Print the four boolean variables isPrice1Less, isPrice2Greater, isPrice1BelowThreshold, and isPrice2AboveThreshold each on a new line using std::cout. Print true or false for each value.

C++

#include 

int main() {
    double price1 = 19.99;
    double price2 = 24.99;
    double threshold = 20.00;

    bool isPrice1Less = price1  price1;
    bool isPrice1BelowThreshold = price1  threshold;

    // Print the boolean results
    // Your code here

    return 0;
}

Hint

Use std::cout and the ternary operator to print true or false for each boolean variable.

Practice

1.

Which of the following relational operators checks if two values are not equal in C++?

easy

A. >=

B. !=

C. <=

D. ==

Solution

1. Step 1: Understand the meaning of each operator

   The operator == checks equality, <= and >= check less or equal and greater or equal respectively.

2. Step 2: Identify the operator for 'not equal'

   The operator != means 'not equal' in C++.

3. Final Answer:

   != -> Option B

4. Quick Check:

   Not equal operator = != [OK]

Hint: Remember: != means not equal in C++ [OK]

Common Mistakes:

• Confusing == with !=
• Thinking <= means not equal
• Mixing up >=
• Using = instead of ==

2.

Which of the following is the correct syntax to compare if a is greater than b in C++?

int a = 5, b = 3;
if (___) {
    // code
}

easy

A. a > b

B. a => b

C. a >< b

D. a >= b

Solution

1. Step 1: Recall the correct operator for 'greater than'

   The operator for 'greater than' is >. The operator >= means 'greater than or equal to'.

2. Step 2: Check syntax correctness

   a > b is the correct syntax to check if a is strictly greater than b. Other options are invalid syntax.

3. Final Answer:

   a > b -> Option A

4. Quick Check:

   Greater than operator = > [OK]

Hint: Use > for greater than, >= for greater or equal [OK]

Common Mistakes:

• Using => instead of >=
• Using >< which is invalid
• Confusing >= with >
• Missing spaces causing syntax errors

3.

What will be the output of the following C++ code?

int x = 7, y = 10;
if (x <= y) {
    std::cout << "Yes";
} else {
    std::cout << "No";
}

medium

A. No

B. 10

C. 7

D. Yes

Solution

1. Step 1: Evaluate the relational expression

   Check if x <= y means 7 is less than or equal to 10, which is true.

2. Step 2: Determine which branch executes

   Since the condition is true, the if block runs and prints "Yes".

3. Final Answer:

   Yes -> Option D

4. Quick Check:

   7 <= 10 is true, so output is Yes [OK]

Hint: Check condition truth to decide output [OK]

Common Mistakes:

• Confusing <= with <
• Assuming else block runs
• Printing variable values instead of strings
• Ignoring the condition result

4.

Find the error in the following C++ code snippet:

int a = 4, b = 9;
if (a = b) {
    std::cout << "Equal";
} else {
    std::cout << "Not Equal";
}

medium

A. Incorrect variable declaration

B. Missing semicolon after if statement

C. Using assignment operator instead of equality operator in if condition

D. Using std::cout incorrectly

Solution

1. Step 1: Identify the operator in the if condition

   The condition uses a = b, which assigns value of b to a instead of comparing.

2. Step 2: Correct the operator for comparison

   To compare, the operator should be ==, so the condition should be a == b.

3. Final Answer:

   Using assignment operator instead of equality operator in if condition -> Option C

4. Quick Check:

   Use == for comparison, not = [OK]

Hint: Use == to compare, = to assign [OK]

Common Mistakes:

• Using = instead of ==
• Forgetting to compare variables
• Assuming assignment returns boolean false
• Ignoring compiler warnings

5.

Given the code below, what will be the output?

int a = 5, b = 5, c = 10;
if (a == b && c > b) {
    std::cout << "Match";
} else if (a != b || c < b) {
    std::cout << "Mismatch";
} else {
    std::cout << "Unknown";
}

hard

A. Match

B. Unknown

C. Mismatch

D. Compilation error

Solution

1. Step 1: Evaluate the first if condition

   Check a == b (5 == 5) is true, and c > b (10 > 5) is true, so the whole condition is true.

2. Step 2: Determine which block executes

   Since the first condition is true, "Match" is printed and the rest is skipped.

3. Final Answer:

   Match -> Option A

4. Quick Check:

   Both conditions true, so output is Match [OK]

Hint: Check && needs both true, || needs one true [OK]

Common Mistakes:

• Confusing && and || operators
• Ignoring short-circuit evaluation
• Assuming else if runs after true if
• Misreading relational comparisons