Built-in data types in C++ - Mini Project: Build & Apply

Understanding Built-in Data Types in C++

📖 Scenario: You are learning how to use basic built-in data types in C++. These types help you store different kinds of information like numbers and letters.

🎯 Goal: You will create variables of different built-in data types, assign values to them, and then print their values to see how they work.

📋 What You'll Learn

Create variables of type int, double, char, and bool with exact names and values.

Create a variable called isAdult of type bool and assign it a value.

Use std::cout to print the values of all variables in the specified order.

💡 Why This Matters

🌍 Real World

Built-in data types are the foundation for storing and working with data in any C++ program, from games to business software.

💼 Career

Understanding data types is essential for programming jobs because it helps you manage memory and data correctly and avoid errors.

1

Create variables of built-in data types

Create an int variable called age and set it to 25. Create a double variable called height and set it to 175.5.

C++

#include 

int main() {
    // Create an int variable called age and set it to 25
    // Create a double variable called height and set it to 175.5
    // Your code here

    return 0;
}

Hint

Use the syntax type variableName = value; to create variables.

2

Add char and bool variables

Create a char variable called initial and set it to 'A'. Create a bool variable called isAdult and set it to true.

C++

#include 

int main() {
    int age = 25;
    double height = 175.5;
    // Create a char variable called initial and set it to 'A'
    // Create a bool variable called isAdult and set it to true
    // Your code here

    return 0;
}

Hint

Remember to use single quotes for char values and true or false for bool.

3

Print all variable values

Use std::cout to print the values of age, height, initial, and isAdult each on a new line.

C++

#include 

int main() {
    int age = 25;
    double height = 175.5;
    char initial = 'A';
    bool isAdult = true;
    // Print age, height, initial, and isAdult each on a new line
    // Your code here

    return 0;
}

Hint

Use std::cout << variable << std::endl; to print each variable on its own line.

4

Run and check the output

Run the program and check that the output shows the values 25, 175.5, A, and 1 each on a new line.

C++

#include 

int main() {
    int age = 25;
    double height = 175.5;
    char initial = 'A';
    bool isAdult = true;

    std::cout << age << std::endl;
    std::cout << height << std::endl;
    std::cout << initial << std::endl;
    std::cout << isAdult << std::endl;

    // Check the output
}

Hint

The bool value true prints as 1 in C++.

Practice

1.

Which built-in data type in C++ is used to store whole numbers without decimals?

easy

A. int

B. double

C. char

D. bool

Solution

1. Step 1: Understand data types for numbers

   Whole numbers without decimals are stored in integer types.

2. Step 2: Identify the integer type in C++

   The int type stores whole numbers like 1, 2, -5.

3. Final Answer:

   int -> Option A

4. Quick Check:

   Whole numbers = int [OK]

Hint: Whole numbers use int type in C++ [OK]

Common Mistakes:

• Choosing double for whole numbers
• Using char for numbers
• Confusing bool with numbers

2.

Which of the following is the correct way to declare a variable of type char in C++?

?

easy

A. char letter = 65

B. char letter = "A";

C. char letter = A;

D. char letter = 'A';

Solution

1. Step 1: Understand char initialization

   Characters must be enclosed in single quotes in C++.

2. Step 2: Check each option

   char letter = 'A'; uses single quotes correctly. char letter = "A"; uses double quotes (string). char letter = A; misses quotes. char letter = 65; uses an int, which is allowed but not typical for char.

3. Final Answer:

   char letter = 'A'; -> Option D

4. Quick Check:

   char uses single quotes for characters [OK]

Hint: Use single quotes for char values [OK]

Common Mistakes:

• Using double quotes for char
• Missing quotes around character
• Assigning int without cast

3.

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

#include <iostream>
int main() {
    bool flag = 0;
    if (flag) {
        std::cout << "True";
    } else {
        std::cout << "False";
    }
    return 0;
}

medium

A. True

B. False

C. 0

D. 1

Solution

1. Step 1: Understand bool initialization

   The variable flag is set to 0, which means false in boolean context.

2. Step 2: Check the if condition

   Since flag is false, the else block runs, printing "False".

3. Final Answer:

   False -> Option B

4. Quick Check:

   bool 0 means false [OK]

Hint: bool 0 means false, else block runs [OK]

Common Mistakes:

• Thinking 0 is true
• Expecting numeric output
• Confusing bool with int

4.

Identify the error in this C++ code snippet:

double price = 9.99;
char letter = "B";
bool isAvailable = true;

medium

A. Incorrect bool value assignment

B. Missing semicolon after double declaration

C. Using double quotes for char variable

D. No errors in the code

Solution

1. Step 1: Check char variable initialization

   The variable letter is declared as char but assigned with double quotes, which is incorrect.

2. Step 2: Verify other lines

   The double and bool declarations are correct with semicolons and proper values.

3. Final Answer:

   Using double quotes for char variable -> Option C

4. Quick Check:

   char needs single quotes, not double [OK]

Hint: char must use single quotes, not double quotes [OK]

Common Mistakes:

• Using double quotes for char
• Missing semicolons
• Wrong bool literals

5.

You want to store a person's age, initial letter of their name, and whether they are a student. Which built-in data types should you use in C++?

medium

A. int for age, char for initial, bool for student status

B. double for age, string for initial, int for student status

C. char for age, int for initial, bool for student status

D. bool for age, char for initial, double for student status

Solution

1. Step 1: Choose type for age

   Age is a whole number, so int is suitable.

2. Step 2: Choose type for initial letter

   Initial is a single character, so char fits.

3. Step 3: Choose type for student status

   Student status is yes/no, so bool is best.

4. Final Answer:

   int for age, char for initial, bool for student status -> Option A

5. Quick Check:

   Whole number = int, letter = char, yes/no = bool [OK]

Hint: Use int for numbers, char for letters, bool for yes/no [OK]

Common Mistakes:

• Using double for age
• Using string for single char
• Using int for boolean values