Anonymous

   #include <stdio.h>
   /* count digits, white space, others */
   main()
   {
        int c, i, nwhite, nother;
        int ndigit[10];
        nwhite = nother = 0;
        for (i = 0; i < 10; ++i)
             ndigit[i] = 0;
        while ((c = getchar()) != EOF)
             if (c >= ’0’ && c <= ’9’)
                  ++ndigit[c-’0’];
             else if (c == ’ ’ || c == ’\n’ || c == ’\t’)
                  ++nwhite;
             else
                  ++nother;
        printf("digits =");
        for (i = 0; i < 10; ++i)
             printf(" %d", ndigit[i]);
        printf(", white space = %d, other = %d\n",
             nwhite, nother);
   }
The output of this program on itself is
   digits = 9 3 0 0 0 0 0 0 0 1, white space = 123, other = 345