shell.c

/*
 * C Program To Sort array in ascending order using Shell Sort.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#define SIZE 100

static inline
void swap(int *a, int *b) { int tmp = *a; *a = *b; *b = tmp; }

void shell(int array[], int n)
{
    for (int i = n / 2; i > 0; i /= 2) {
        for (int j = i; j < n; j++) {
            for (int k = j - i; k >= 0; k = k - i) {
                if (array[k + i] > array[k]) break;
                else swap(&array[k], &array[k + i]);
            }
        }
    }
}

int main(int argc, char *argv[])
{
    int array[SIZE];

    printf("%s - %i\n", argv[0], SIZE);

    // create an array of random ints
    srand(time(NULL));
    for (int i = 0; i < SIZE; i++) array[i] = rand();

    shell(array, SIZE);

    // output array
    for (int i = 0; i < SIZE; i++) printf("%i\n", array[i]);

    return 0;
}