shell_sort.c

    #include <stdio.h>    
    int shell(int a[], int n)  
    {  
        for (int interval = n/2; interval > 0; interval /= 2)  
        {  
            for (int i = interval; i < n; i += 1)  
            {  
                int temp = a[i];  
                int j;        
                for (j = i; j >= interval && a[j - interval] > temp; j -= interval)  
                    a[j] = a[j - interval];  

                a[j] = temp;  
            }  
        }  
        return 0;  
    }  
    void printArr(int a[], int n) 
    {  
        int i;  
        for (i = 0; i < n; i++)  
            printf("%d ", a[i]);  
    }    
    int main()  
    {  
        int a[] = { 33, 31, 40, 8, 12, 17, 25, 42 };  
        int n = sizeof(a) / sizeof(a[0]);  
        printf("Before sorting array elements are - \n");  
        printArr(a, n);  
        shell(a, n);  
        printf("\nAfter applying shell sort, the array elements are - \n");    
        printArr(a, n);  
        return 0;  
    }