Built-in data types in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are built-in data types in C++?

Built-in data types are the basic types provided by C++ to store simple values like numbers, characters, and boolean values. Examples include int, char, float, double, and bool.

beginner

What is the difference between int and float in C++?

int stores whole numbers without decimals, while float stores numbers with decimals (fractional parts).

beginner

What is the size of a bool type in C++ and what values can it hold?

bool typically uses 1 byte and can hold only two values: true or false.

beginner

Which built-in data type would you use to store a single character in C++?

You use the char type to store a single character, like 'a' or 'Z'.

intermediate

What is the difference between float and double?

double stores floating-point numbers with double the precision of float. It uses more memory but is more accurate for decimals.

Which C++ built-in data type is used to store true or false values?

A int

B bool

C char

D float

bool is the type designed to hold true or false values.

What type would you use to store the number 42 in C++?

A bool

B float

C char

D int

The number 42 is a whole number, so int is the correct type.

Which data type can store decimal numbers with more precision?

A double

B char

C int

D float

double stores decimal numbers with more precision than float.

What is the size of a char in C++?

A 1 byte

B 2 bytes

C 4 bytes

D 8 bytes

char typically uses 1 byte to store a single character.

Which of these is NOT a built-in data type in C++?

A int

B double

C string

D bool

string is not a built-in data type; it is a class in the standard library.

List the main built-in data types in C++ and describe what kind of values each stores.

Think about numbers, letters, and true/false values.

Explain the difference between float and double in terms of precision and memory.

One stores decimals more accurately but uses more memory.

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