Arithmetic Operators in C++

Arithmetic operators are symbols used to perform mathematical operations on values.

int a = 10;
int b = 5;

int result = a + b;

Here, + is an arithmetic operator.

The + operator adds two values.

int a = 10;
int b = 20;

int sum = a + b;

std::cout << sum;

The result is 30.

Two or more variables can be added together.

int first = 25;
int second = 15;

int total = first + second;

std::cout << total;

The output is 40.

The addition operator can also be used with floating-point values.

double price1 = 99.50;
double price2 = 50.25;

double total = price1 + price2;

std::cout << total;

The result is 149.75.

The - operator subtracts the right operand from the left operand.

int a = 50;
int b = 20;

int result = a - b;

std::cout << result;

The result is 30.

If the second value is larger, subtraction can produce a negative result.

int a = 20;
int b = 50;

int result = a - b;

std::cout << result;

The result is -30.

The * operator multiplies two values.

int price = 100;
int quantity = 5;

int total = price * quantity;

std::cout << total;

The result is 500.

double price = 99.50;
double quantity = 2;

double total = price * quantity;

std::cout << total;

The result is 199.

The / operator is used to divide one value by another.

int total = 100;
int students = 5;

int result = total / students;

std::cout << result;

The result is 20.

When both operands are integers, division performs integer division. The fractional part is discarded.

int a = 5;
int b = 2;

int result = a / b;

The result is 2, not 2.5.

If at least one operand is a floating-point value, the division can produce a floating-point result.

double a = 5;
double b = 2;

double result = a / b;

std::cout << result;

The result is 2.5.

You can explicitly convert an integer before division.

int a = 5;
int b = 2;

double result =
    static_cast<double>(a) / b;

std::cout << result;

The result is 2.5.

The % operator returns the remainder after integer division.

int result = 17 % 5;

std::cout << result;

The result is 2.

The modulus operator is commonly used to check whether a number is even or odd.

int number = 10;

if (number % 2 == 0) {
    std::cout << "Even";
} else {
    std::cout << "Odd";
}

If the remainder is zero, the number is even.

The unary + operator is applied to a single operand and preserves its value.

int number = 10;

int result = +number;

The value of result is 10.

The unary - operator changes the sign of its operand.

int number = 10;

int result = -number;

std::cout << result;

The result is -10.

Multiple arithmetic operators can be combined in one expression.

int a = 10;
int b = 5;
int c = 2;

int result = a + b * c;

Multiplication is performed before addition according to operator precedence.

Parentheses can be used when you want a particular part of an expression to be evaluated first.

int a = 10;
int b = 5;
int c = 2;

int result = (a + b) * c;

Here, a + b is evaluated before multiplication.

int a = 20;
int b = 10;

int sum = a + b;
int difference = a - b;
int product = a * b;
int quotient = a / b;
int remainder = a % b;

All five basic arithmetic operators are demonstrated here.

#include <iostream>

int main() {

    int a, b;

    std::cout << "Enter first number: ";
    std::cin >> a;

    std::cout << "Enter second number: ";
    std::cin >> b;

    std::cout << "Sum = " << a + b;

    return 0;
}

The values entered by the user are used in an arithmetic operation.

#include <iostream>

int main() {

    double a, b;

    std::cout << "Enter first number: ";
    std::cin >> a;

    std::cout << "Enter second number: ";
    std::cin >> b;

    std::cout << "Addition: " << a + b << std::endl;
    std::cout << "Subtraction: " << a - b << std::endl;
    std::cout << "Multiplication: " << a * b << std::endl;

    if (b != 0) {
        std::cout << "Division: " << a / b << std::endl;
    }

    return 0;
}

A program should not attempt division by zero.

int a = 10;
int b = 0;

// a / b;   // Do not do this

Always validate a divisor before performing division when it may be zero.

The actual result type follows C++'s usual arithmetic conversions.

Arithmetic operations can also be combined with assignment.

int number = 10;

number += 5;
number -= 2;
number *= 2;
number /= 4;

Each statement performs an arithmetic operation and assigns the result back to number.

#include <iostream>

int main() {

    int english = 80;
    int maths = 90;
    int science = 85;

    int total = english + maths + science;

    double average =
        static_cast<double>(total) / 3;

    std::cout << "Total = " << total << std::endl;
    std::cout << "Average = " << average;

    return 0;
}

The total uses addition, while the average uses division with an explicit conversion to double.

#include <iostream>

int main() {

    int a = 25;
    int b = 4;

    std::cout << "Addition: "
              << a + b << std::endl;

    std::cout << "Subtraction: "
              << a - b << std::endl;

    std::cout << "Multiplication: "
              << a * b << std::endl;

    std::cout << "Integer Division: "
              << a / b << std::endl;

    std::cout << "Remainder: "
              << a % b << std::endl;

    std::cout << "Decimal Division: "
              << static_cast<double>(a) / b
              << std::endl;

    return 0;
}

• Forgetting that integer division discards the fractional part.
• Using the modulus operator with floating-point operands.
• Dividing by zero.
• Ignoring the effect of operator precedence.
• Forgetting parentheses when a specific evaluation order is required.
• Using a data type that cannot represent the required result correctly.