Functions and Default Arguments

C++ functions can give parameters a default value, used when the caller omits that argument:

double power(double base, int exponent = 2) {
    double result = 1;
    for (int i = 0; i < exponent; i++) {
        result *= base;
    }
    return result;
}

std::cout << power(5) << std::endl;    // 25 — exponent defaults to 2
std::cout << power(5, 3) << std::endl; // 125

Common mistakes

• Giving a default value to a parameter that comes before one without a default — every parameter after the first one with a default must also have one.