truc.c

#include<stdio.h>
#include<stdlib.h>
typedef struct Node
{
  int data;
  struct Node *next;
}node;
void insert(node *pointer, int data)
{
  /* Iterate through the list till we encounter the last node.*/
  while(pointer->next!=NULL)
    {
      pointer = pointer -> next;
    }
  /* Allocate memory for the new node and put data in it.*/
  pointer->next = (node *)malloc(sizeof(node));
  pointer = pointer->next;
  pointer->data = data;
  pointer->next = NULL;
}
int find(node *pointer, int key)
{
  pointer =  pointer -> next; //First node is dummy node.
  /* Iterate through the entire linked list and search for the key. */
  while(pointer!=NULL)
    {
      if(pointer->data == key) //key is found.
	{
	  return 1;
	}
      pointer = pointer -> next;//Search in the next node.
    }
  /*Key is not found */
  return 0;
}
void delete(node *pointer, int data)
{
  /* Go to the node for which the node next to it has to be deleted */
  while(pointer->next!=NULL && (pointer->next)->data != data)
    {
      pointer = pointer -> next;
    }
  if(pointer->next==NULL)
    {
      printf("Element %d is not present in the list\n",data);
      return;
    }
  /* Now pointer points to a node and the node next to it has to be removed */
  node *temp;
  temp = pointer -> next;
  /*temp points to the node which has to be removed*/
  pointer->next = temp->next;
  /*We removed the node which is next to the pointer (which is also temp) */
  free(temp);
  /* Beacuse we deleted the node, we no longer require the memory used for it . 
           free() will deallocate the memory.
  */
  return;
}
void print(node *pointer)
{
  if(pointer==NULL)
    {
      return;
    }
  printf("%d ",pointer->data);
  print(pointer->next);
}
int main()
{
  /* start always points to the first node of the linked list.
     temp is used to point to the last node of the linked list.*/
  node *start,*temp;
  start = (node *)malloc(sizeof(node));
  temp = start;
  temp -> next = NULL;
  /* Here in this code, we take the first node as a dummy node.
           The first node does not contain data, but it used because to avoid handling special cases
           in insert and delete functions.
  */
  printf("1. Insert\n");
  printf("2. Delete\n");
  printf("3. Print\n");
  printf("4. Find\n");
  while(1)
    {
      int query;
      scanf("%d",&query);
      if(query==1)
	{
	  int data;
	  scanf("%d",&data);
	  insert(start,data);
	}
      else if(query==2)
	{
	  int data;
	  scanf("%d",&data);
	  delete(start,data);
	}
      else if(query==3)
	{
	  printf("The list is ");
	  print(start->next);
	  printf("\n");
	}
      else if(query==4)
	{
	  int data;
	  scanf("%d",&data);
	  int status = find(start,data);
	  if(status)
	    {
	      printf("Element Found\n");
	    }
	  else
	    {
	      printf("Element Not Found\n");

	    }
	}
    }


}