The number of digits

#include <iostream>

int digits(int num)
{
    int amount = 0;
    while (num != 0)
    {
        num /= 10;
        amount++;
    }
    return amount;
}

int main()
{
    int num;
    std::cout << "Input number: ";
    std::cin >> num;
    std::cout << "The number of digits: " << digits(num) << std::endl;
    return 0;
}