C++ Math

Every program eventually needs to do a little math, whether it is adding up a bill, measuring distance, or rounding a price. C++ handles simple arithmetic with the ordinary operators you already know, and it provides extra functions for anything more advanced.

Basic arithmetic

You do not need any special library for the everyday operations. The operators + (add), - (subtract), * (multiply), / (divide), and % (remainder) are part of the core language and work on numbers directly.

#include <iostream>
using namespace std;

int main() {
  int a = 20;
  int b = 6;

  cout << "Sum: " << a + b << "\n";        // 26
  cout << "Product: " << a * b << "\n";    // 120
  cout << "Quotient: " << a / b << "\n";   // 3 (integer division)
  cout << "Remainder: " << a % b << "\n";  // 2
  return 0;
}

min() and max()

Two of the most useful math helpers are max() and min(). They return the larger or smaller of two values, which saves you from writing an if statement every time. Both are available through the <algorithm> header.

#include <iostream>
#include <algorithm>
using namespace std;

int main() {
  int score1 = 78;
  int score2 = 91;

  cout << "Best score: " << max(score1, score2) << "\n";  // 91
  cout << "Worst score: " << min(score1, score2) << "\n"; // 78
  return 0;
}

The <cmath> library

For more advanced math, include the <cmath> header. It unlocks functions such as sqrt() for square roots, pow() for exponents, round() for rounding to the nearest whole number, and abs() for the absolute value. These functions usually return a double.

#include <iostream>
#include <cmath>
using namespace std;

int main() {
  cout << sqrt(64) << "\n";      // 8
  cout << pow(2, 10) << "\n";    // 1024 (2 to the power of 10)
  cout << round(4.7) << "\n";    // 5
  cout << abs(-15) << "\n";      // 15
  return 0;
}