LinkedList Elements Swap Problem In C

I wrote a program that has many functionalities but I can not swap 2 elements of 2 nodes in the linked list.Actually I can swap 2 nodes by changing their links but I can not swap 2 elements when the user requested 2 elements swapping.Here is my code without any swap operation.Again I have to say I want to do this swap operation by swapping 2 node elements not changing node links.How can I get rid of this problem?Any help will be appreciated.

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

struct node{
  int data;
  struct node *next;
     };
typedef struct node nodetype;

void insert(int ,struct node **);
void display(struct node *);
void search(int, struct node *);
void delete(int, struct node **);
int main(void){

    nodetype *p;
    p=NULL;
    int x=0,choice;
    int s_no,k,r_no;


    while(x!=1){
        printf("enter 1 for insert\n");
        printf("enter 2 for display\n");
        printf("enter 3 for search\n");
        printf("enter 4 for delete\n");

        printf("enter 0 for exit\n");
        fflush(stdout);
        scanf("%d",&choice);
        if(choice==1){
            printf("enter inserted  no\n");
            fflush(stdout);
             scanf("%d",&k);
            insert(k,&p);
        }

        else if(choice==2)
            display(p);
        else if(choice==3){
            printf("enter searched no\n");
            scanf("%d",&s_no);
      开发者_StackOverflow      search(s_no, p);
        }
        else if(choice==4){
            printf("enter deleted no\n");
            scanf("%d",&r_no);
            delete(r_no,&p);
                }
        else
            printf("invalid choice\n");
    }
    return 0;
}
void display ( struct node *p)
{
    printf("the content is:\n");
    if(p==NULL)
        printf("the link is empty\n");
    while ( p != NULL )
    {
        printf ( "%d ", p -> data ) ;
        p = p -> next ;
    }
 printf ( "\n" ) ;
}

void search(int no, struct node *p){
   nodetype * loc;
   for(loc=p;loc!=NULL;loc=loc->next)
    {
     if(no==loc->data){
       printf("\nthe number exist in the list\n");
       return;
     }

    }
   printf("\nthe number is not exist in the \n");
 }
void insert(int x,struct node **p)
{
    struct node *r,*temp=*p;
    r = (struct node *)malloc ( sizeof (struct node)) ;
    r ->data = x ;
    r->next=NULL;
    if ( *p == NULL)
    {
        *p = r ;
    }
    else
    {
        while(temp->next!= NULL)
        {
                  temp=temp->next;
        }

     temp->next=r;
    }
}
void delete(int num, struct node **p){
  struct node *temp,*x;
  temp=*p;
  x= NULL;
  while (temp->next !=NULL){
    if(temp->data == num)
     {
      if (x==NULL)
       {
        *p = temp->next;
        free(temp);
        return;
       }
      else
       {
        x->next = temp->next;
        free(temp);
        return;
       }
     }
    x=temp;
    temp=temp->next;
  }
  printf(" No such entry to delete ");
}

---

I attempted swap operation with using user entered numbers.For instance,the user entered 12 and 45 in order to swap in the linkedlist.How can I do that?

I would suggest you extend the existing function with return values, (not tested just the idea)

nodetype * search(int no, struct node *p){
   nodetype * loc;
   for(loc=p;loc!=NULL;loc=loc->next)
    {
     if(no==loc->data){
       printf("\nthe number exist in the list\n");
       return loc;
     }

    }
   printf("\nthe number is not exist in the \n");
   return NULL;
 }

After that you call search for both values entered by the user. Then you swap the values in place without changing any pointer references simply be assigning new values. Of course you need to check whether the nodes were actually found (not NULL).

nodetype *node1;
nodetype *node2;

node1 = search( userInput1, &p );
node2 = search( userInput2, &p );

int tmp_data = node1->data;
node1->data = node2->data;
node2->data = tmp;