C :: How To Count Total Characters From A Text File

I'm supposed to write a program to read a text file and display the following:

a) alphabetic letters //finished with
b) digits // finished with
c) other characters that are not alphabetic letters and not digits //finished with
d) total characters read

The bold part above confused me, by total characters, does it mean the alphabetic letters + other characters? how would I put that in my code?

Code:
#include <stdio.h>
int main (void)
{
int curCh;
int countCh = 0;

[Code]....