write a program to input a number and print the number of digits used.

Question

without array

Answer 1

std::ceil(std::log10(std::abs(x))); does the charm, too. :-)
Nevertheless, you have to include <cmath>.

Answer 2

#include <iostream>

void main()
{
int x, n(0);
std::cin >> x;
while (x != 0)
{
x /= 10;
++n;
}
std::cout << n;
}

Not tested it but I believe this will work for any positive integer.

Answer 3

thanks man it works