Finding the number of digits of an integer

Question

What is the best method to find the number of digits of a positive integer?

I have found this 3 basic methods:

• conversion to string

Answer 1

Keep it simple:

long long int a = 223452355415634664;

int x;
for (x = 1; a >= 10; x++)
{
   a = a / 10;
}

printf("%d", x);