Arithmetic Operators

C++ Arithmetic Operators

Arithmetic operators do the math: +, -, *, /, and %.

The five operators

• + adds.
• - subtracts.
• * multiplies.
• / divides.
• % gives the remainder of a division.

A small program

#include <iostream>
using namespace std;

int main() {
  int x = 10;
  int y = 3;
  cout << x + y << endl;   // 13
  cout << x - y << endl;   // 7
  cout << x * y << endl;   // 30
  cout << x / y << endl;   // 3
  cout << x % y << endl;   // 1
  return 0;
}

Integer division truncates

When both numbers are whole numbers (int), the result is a whole number. 10 / 3 is not 3.33; it is 3. The decimal part is simply dropped.

cout << 10 / 3 << endl;     // 3
cout << 10.0 / 3 << endl;   // about 3.33333

To keep the decimals, make at least one number a double.

The remainder is left over

10 % 3 is 1: after putting two whole 3s into 10, there is 1 left over. The % operator answers that question.

TL;DR

• Arithmetic operators: +, -, *, /, %.
• Integer divided by integer truncates the decimals.
• Use a double to preserve a decimal result.
• % gives the remainder of a division, not the quotient.