c++ length of int

  string txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
cout << "The length of the txt 
  string is: " << txt.length(); 

// array::size
#include <iostream>
#include <array>

int main ()
{
  std::array<int,5> myints;
  std::cout << "size of myints: " << myints.size() << std::endl;
  std::cout << "sizeof(myints): " << sizeof(myints) << std::endl;

  return 0;
}

unsigned int number_of_digits = 0;

do {
     ++number_of_digits; 
     n /= base;
} while (n);

sizeof(num);