The int Data Type in C++

In C++, the int data type is used to store whole numbers (i.e., integers) without any fractional or decimal part. It is one of the most commonly used data types in programming for representing counts, indices, and simple arithmetic.

What is int?

The int keyword stands for integer. It is a signed data type by default, which means it can store both positive and negative whole numbers.

Declaration and Initialization

Declaring an int variable is straightforward. You use the int keyword followed by the variable name and optionally assign an initial value.

#include <iostream>
 
int main() {
    int age = 25;
    std::cout << "Age: " << age << std::endl;
    return 0;
}

Here:

• int age = 25; creates a variable named age and stores the integer value 25.
• std::cout outputs the value to the console.

Valid Integer Values

The int type stores whole numbers in the following range:

Note: The exact range may depend on the system and compiler.

Arithmetic Operations

Integers support all basic arithmetic operations: addition, subtraction, multiplication, division, and modulus (remainder).

#include <iostream>
 
int main() {
    int a = 20;
    int b = 7;
 
    std::cout << "Sum: " << a + b << std::endl;
    std::cout << "Quotient: " << a / b << std::endl;
    std::cout << "Remainder: " << a % b << std::endl;
 
    return 0;
}

Output:

Sum: 27
Quotient: 2
Remainder: 6

Division between integers discards any fractional part.

Integer Overflow

Be cautious of exceeding the maximum or minimum limits of int, as this results in integer overflow, which causes unpredictable behavior.

#include <iostream>
#include <climits>
 
int main() {
    int max = INT_MAX;
    std::cout << "Max int: " << max << ", Overflow: " << (max + 1) << std::endl;
    return 0;
}

This may print a negative number due to overflow.

Type Modifiers

C++ allows the use of type modifiers with int to adjust its size and sign:

Practice Problem 1: Sum of Two Numbers

Write a program that takes two integers and prints their sum.

#include <iostream>
 
int main() {
    int x = 15, y = 35;
    int sum = x + y;
    std::cout << "Sum: " << sum << std::endl;
    return 0;
}

Practice Problem 2: Even or Odd

Determine whether a given number is even or odd using the modulus operator.

#include <iostream>
 
int main() {
    int num = 42;
    if (num % 2 == 0)
        std::cout << "Even" << std::endl;
    else
        std::cout << "Odd" << std::endl;
    return 0;
}

Practice Problem 3: Find the Largest of Three Numbers

#include <iostream>
 
int main() {
    int a = 14, b = 27, c = 19;
 
    int largest = (a > b) ? (a > c ? a : c) : (b > c ? b : c);
    std::cout << "Largest number: " << largest << std::endl;
 
    return 0;
}

Summary

The int data type is fundamental in C++ and is often the default choice when working with numeric values that don’t require fractions. Understanding how it works, its range, and operations is crucial for writing reliable and efficient code.