Counting digits using while loop

Question

I was recently making a program which needed to check the number of digits in a number inputted by the user. As a result I made the following code:

int x;            


        

Answer 1

If x is an integer, and by "built in function" you aren't excluding logarithms, then you could do

double doub_x=double(x);
double digits=log(abs(doub_x))/log(10.0);
int digits= int(num_digits);