Built-in data types in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of integer and floating-point operations

What is the output of the following C++ code?

C++

#include <iostream>
int main() {
    int a = 5;
    double b = 2.0;
    std::cout << a / b << std::endl;
    return 0;
}

A 2

B 2.50

C 2.5

D 2.0

💡 Hint

Remember that dividing an int by a double results in a double.

The integer 5 is promoted to double 5.0, then divided by 2.0, resulting in 2.5.

❓ Predict Output

intermediate

Size of built-in data types

What is the output of this C++ code on a typical 64-bit system?

C++

#include <iostream>
int main() {
    std::cout << sizeof(char) << "," << sizeof(int) << "," << sizeof(long long) << std::endl;
    return 0;
}

A 1,4,8

B 1,8,8

C 1,4,4

D 2,4,8

💡 Hint

On most 64-bit systems, char is 1 byte, int is 4 bytes, and long long is 8 bytes.

The sizes reflect typical memory allocation: char=1 byte, int=4 bytes, long long=8 bytes.

🧠 Conceptual

advanced

Understanding signed and unsigned integer behavior

What will be the output of this C++ code snippet?

C++

#include <iostream>
int main() {
    unsigned int x = 0;
    std::cout << x - 1 << std::endl;
    return 0;
}

A 4294967295

B 0

C -1

D Compilation error

💡 Hint

Unsigned integers wrap around when subtracting beyond zero.

Subtracting 1 from 0 in unsigned int wraps to the maximum value (2^32 - 1 = 4294967295).

❓ Predict Output

advanced

Boolean type and implicit conversion

What is the output of this C++ code?

C++

#include <iostream>
int main() {
    bool flag = 5;
    std::cout << flag << std::endl;
    return 0;
}

A 5

B 1

C true

D 0

💡 Hint

Any non-zero integer assigned to a bool becomes true (1).

In C++, bool stores either 0 (false) or 1 (true). Assigning 5 converts to true (1).

🔧 Debug

expert

Identify the error in this code using built-in types

What error does this C++ code produce when compiled?

C++

#include <iostream>
int main() {
    int x = 10;
    double y = 3.5;
    int z = x / y;
    std::cout << z << std::endl;
    return 0;
}

A No error, output is 3

B Compilation error: cannot assign double to int

C Runtime error: division by zero

D No error, output is 2

💡 Hint

Division of int by double results in double, then assigned to int truncates the decimal.

x / y is 10 / 3.5 = 2.857..., assigned to int z truncates to 2, no errors occur.

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