I'm just trying to find out the length of a long int in C.

I'm trying to accept a number from the user as :

long int i;

printf("Enter a no: ");
scanf("&ld", &i);



The user can give any integer for i -- lets say from 1 digit to 20 digits
So, how do i find the length of the number he gives?
Suppose say he enters " 62351235123512" it should display length=14

Also, I'm unable to get if i need to specify as 'long' or 'double' when declaring ' int i' ??
Please help me on this.
I've tried using ' itoa' function and also sprintf() function but unable to get it !!