اكتب برنامج بلغة C لإدراج عقدة في نهاية قائمة مرتبطة دائرية (circular linked list)

/*Write a program in C to insert a node at the end of a circular linked list*/

#include <stdio.h>
#include <stdlib.h>

struct node {
    int num;
    struct node * nextptr;
}*stnode;

struct node *tail,*p,*q,*store; 

void ClListcreation(int n);
void ClLinsertNodeAtEnd(int num);
void displayClList(int a);

int main()
{
    int n,num1,a,insPlc;
    stnode = NULL;
	printf("\n\n Circular Linked List : Insert a node at the end of a circular linked list :\n");
	printf("--------------------------------------------------------------------------------\n");	   	
    printf(" Input the number of nodes : ");
    scanf("%d", &n);
    ClListcreation(n); 
    a=1;
    displayClList(a);
    printf(" Input the data to be inserted : ");
    scanf("%d", &num1);    
    ClLinsertNodeAtEnd(num1);  	
    a=2;
    displayClList(a);	
    return 0;
}

void ClListcreation(int n)
{
    int i, num;
    struct node *preptr, *newnode;
    if(n >= 1)
    {
        stnode = (struct node *)malloc(sizeof(struct node));
        printf(" Input data for node 1 : ");
        scanf("%d", &num);
        stnode->num = num;
        stnode->nextptr = NULL;
        preptr = stnode;
        for(i=2; i<=n; i++)
        {
            newnode = (struct node *)malloc(sizeof(struct node));
            printf(" Input data for node %d : ", i);
            scanf("%d", &num);
            newnode->num = num;
            newnode->nextptr = NULL;	// next address of new node set as NULL
            preptr->nextptr = newnode;	// previous node is linking with new node
            preptr = newnode;   		// previous node is advanced
        }
        preptr->nextptr = stnode; 		//last node is linking with first node
    }
}

void ClLinsertNodeAtEnd(int num1)
{
		int a;
		a=num1;
		struct node *temp=(struct node*)malloc(sizeof(struct node));
		temp->num=a;
		p=stnode;
		while(p->nextptr!=stnode)
		{
			p=p->nextptr;
		}
		p->nextptr=temp;
		temp->nextptr=stnode;
}

void displayClList(int m)
{
    struct node *tmp;
    int n = 1;
    if(stnode == NULL)
    {
        printf(" No data found in the List yet.");
    }
    else
    {
        tmp = stnode;
        if (m==1)
        {
        printf("\n Data entered in the list are :\n");
        }
        else
        {
         printf("\n After insertion the new list are :\n");   
        }        
        do {
            printf(" Data %d = %d\n", n, tmp->num);

            tmp = tmp->nextptr;
            n++;
        }while(tmp != stnode);
    }
}