Built-in data types in C++

Introduction

Built-in data types let you store different kinds of information in your program, like numbers or letters.

When you need to store whole numbers like counting apples.

When you want to store decimal numbers like prices or measurements.

When you want to store single characters like a letter or symbol.

When you want to store true or false values to make decisions.

When you want to store larger numbers or precise decimal values.

Syntax

C++

type variableName;

// Examples:
int age;
double price;
char letter;
bool isOpen;

type is the kind of data you want to store.

variableName is the name you give to your storage box.

Examples

This stores the whole number 10 in a variable named count.

C++

int count = 10;

This stores a decimal number 36.5 in temperature.

C++

double temperature = 36.5;

This stores a single letter 'A' in grade.

C++

char grade = 'A';

This stores a true/false value indicating if it is raining.

C++

bool isRaining = false;

Sample Program

This program creates variables of different built-in types and prints their values.

C++

#include <iostream>

int main() {
    int apples = 5;
    double price = 1.25;
    char firstLetter = 'A';
    bool isOpen = true;

    std::cout << "Apples: " << apples << "\n";
    std::cout << "Price: $" << price << "\n";
    std::cout << "First letter: " << firstLetter << "\n";
    std::cout << "Store open? " << (isOpen ? "Yes" : "No") << "\n";

    return 0;
}

Important Notes

Use int for whole numbers without decimals.

Use double for numbers with decimals.

Use char for single characters inside single quotes.

Use bool for true or false values.

Summary

Built-in data types store basic kinds of information.

Common types include int, double, char, and bool.

Choose the type based on the kind of data you want to keep.

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