Thread: Code Review Request: Number Histogram

Hello! I've been wanting to learn C a while now and finally decided to pick up Kernighan and Ritchie's ANSI C. One of the 'projects' is to create a numbered histogram, which I successfully did.

I just would like to know if this could be further optimized or any other pointers you all may have.

Thanks!

Code:

/* Histogram for counting input of numbers.
   Troy Martin, Beef Erikson Studios 2018 */


#include <stdio.h>


int main()
{
    /* forward declares */
    int c, i, j;
    int ndigit[10];


    /* variable / array assignment */
    int number = 0;
    for (i = 0; i < 10; ++i)
        ndigit[i] = 0;


    /* reads input and puts numbers into corresponding array index */
    while ((c = getchar()) != EOF)
        if (c >= '0' && c <= '9')
            ++ndigit[c-'0'];
    printf("\n\n");


    /* finds highest number */
    for (i = 0; i < 10; ++i)
        if (ndigit[i] > number)
            number = ndigit[i];


    /* display histogram based on highest number */
    for (i = 0; i < number; --number) {
        for (j = 0; j < 10; ++j) {
            if (ndigit[j] >= number)
                printf("   *");
            else
                printf("    ");
        }
        printf("\n");
    }


    /* prints footer */
    for (i = 0; i < 10; ++i)
        printf("%4d", i);
    printf("\n\n  Histogram of times each number was used.\n\n");
}

Here it is running: