Linked List insertion sort

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>

struct node
{
    node *prev;
    int x;
    node *next;
};

node *ptr = 0, *ptr2 = 0, *ptr3 = 0, *ptr4 = 0, *ptr5 = 0, *ptr6 = 0, *ptr7 = 0, *ptr8 = 0;

int main()
{
    int t, i, j, k, l, a, b, c, d, y, z, n;
    char ch;

    ptr4 = (node *)malloc(sizeof(node));
    ptr4->x = -1919191;
    ptr4->prev = 0;
    ptr4->next = 0;


    scanf("%d", &t);
    getchar();
    for (i = 1; i <= t; i++)
    {
        ptr2 = ptr4;
        ch = getchar();
        getchar();
        scanf("%d", &n);
        getchar();

        if (ch == 105)
        {
            printf("List: ");
            ptr->next = (node *)malloc(sizeof(node));
            ptr = ptr->next;
            ptr->x = n;
            ptr->next = 0;
            ptr->prev = ptr3;
            ptr3 = ptr;

            ptr2 = ptr;
            for (; ;)
            {
                b = ptr2->x;
                ptr7 = ptr2->prev;
                if (ptr7->x == -1919191) break;
                a = ptr7->x;
                if (a > b)
                {
                    ptr7->x = b;
                    ptr2->x = a;
                }
                ptr2 = ptr2->prev;
            }

            ptr2 = ptr4;
            while(true)
            {
                ptr2 = ptr2->next;
                printf("%d ", ptr2->x);
                if (ptr2->next == 0) break;
            }
            putchar(10);
        }

        if (ch == 105)
        {
            printf("List: ");
            ptr2 = ptr4;
            for (; ;)
            {


                if (ptr2->x > n)
                {
                    ptr8 = ptr2->prev;
                    ptr = ptr8;
                    ptr8->next = (node *)malloc(sizeof(node));
                    ptr8 = ptr8->next;
                    ptr8->x = n;
                    ptr8->prev = ptr;
                    ptr8->next = ptr2;
                    break;
                }

				if (ptr2->next == 0)
                {
                    ptr8 = ptr2;
                    ptr2->next = (node *)malloc(sizeof(node));
                    ptr2 = ptr2->next;
                    ptr2->x = n;
                    ptr2->next = 0;
                    ptr2->prev = ptr8;
                    break;
                }

                ptr2 = ptr2->next;
            }


            ptr2 = ptr4;
            while(true)
            {
                ptr2 = ptr2->next;
                printf("%d ", ptr2->x);
                if (ptr2->next == 0) break;
            }
            putchar(10);
        }

        if (ch == 100)
        {
            d = 0;
            for (; ;)
            {
                ptr2 = ptr2->next;
                if (ptr2->x == n)
                {
                    printf("%d Deleted\n", n);
                    ptr5 = ptr2->prev;
                    ptr6 = ptr5;
                    ptr5->next = ptr2->next;
                    ptr5 = ptr5->next;
                    ptr5->prev = ptr6;
                    d = 1;
                    break;
                }
                if (ptr2->next == 0) break;
            }
            if (d == 0) printf("%d Not Found\n", n);
        }

        if (ch == 115)
        {
            ptr2 = ptr4, d = 0;
            for (; ;)
            {
                ptr2 = ptr2->next;
                if (ptr2->x == n)
                {
                    printf("%d Found\n", n);
                    d = 1;
                    break;
                }
                if (ptr2->next == 0) break;
            }
            if (d == 0) printf("%d Not Found\n", n);
        }
    }
    return 0x0;
}