#include <stdio.h>      /* using printf, fgets, stdin, BUFSIZ */
#include <stdlib.h>     /* using exit */
#include <string.h>     /* using strlen */

int main()
{
    int count = 0;          // Count the number of numeric digits.
    char input[BUFSIZ];
    char * promptPartA = "Please enter lines of text, followed by\n";
    char * promptPartB = "an empty line (just <enter/return>) to exit:\n";

    printf("%s%s", promptPartA, promptPartB);
    while (fgets (input, BUFSIZ, stdin))   /* fgets returns NULL if EOF */
    {
        int  i;
        int  stringLength = strlen(input);

        /* Remove newline if it is there by replacing it with a null byte. */
        if ( stringLength > 0 && input[stringLength-1] == '\n' )
        {
            input[stringLength-1] = '\0';
            stringLength--;
        }
        /* On Windows, there might also be a carriage return; remove it too. */
        if ( stringLength > 0 && input[stringLength - 1] == '\r')
        {
            input[stringLength-1] = '\0';
            stringLength--;
        }

        /* If there is no input, we're done. */
        if ( stringLength == 0 )
        {
            break;      // break out of loop
        }

        /* Include characters in the range of '0' - '9' in the count.
         */
        for ( i = 0; i < stringLength; i++ )
        {
            if ( input[i] >= '0' && input[i] <= '9' )
            {
                count++;
            }
        }
    }

    /* Display the count of numeric characters. */
    printf("\nThere were %d numeric characters in the input.\n", count);

    exit(0);
}