C : Singly Linked List

Soalan :
Write a C program to simulate an ordinary queue using a singly linked list.

Jawapan:

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

struct node
{
 int data;
 struct node *link;
}; struct node *cur,*first,*last;

 void create();
 void insert_rear();
 void delete_front();
 void display();

void create()
{

 printf("\n Enter the first element: ");
 cur=(struct node *)malloc(sizeof(struct node));
 scanf("%d",&cur->data);
 cur->link=NULL;
 first=cur;
 last=cur;
}

void insert_rear()
{
 printf("\n Enter the next element: ");
 cur=(struct node *)malloc(sizeof(struct node));
 scanf("%d",&cur->data);
 cur->link=NULL;
 last->link=cur;
 last=cur;
}
void delete_front()
{
 if(first==NULL)
 {
  printf("\t\n Queue is empty\n");
 }
 else
 {
  cur=first;
  first=first->link;
  cur->link=NULL;
  printf("\n Deleted element is %d\n",cur->data);
  free(cur);
 }
}
void display()
{
 cur=first;
 printf("\n");
 while(cur!=NULL)
 {
  printf("\t%d",cur->data);
  cur=cur->link;
 }
}

void main()
{
 int ch;
 system("cls");
 create();
 display();
 while(1)
 {
  printf("\n--------------------------");
  printf("\n 1.INSERT \n 2.DELETE \n");
  printf("\n Enter your choice >> ");
  scanf("%d",&ch);

  switch(ch)
  {
   case 1:
    insert_rear();
    display();
    break;
   case 2:
    delete_front();
    display();
    break;
   default:
    exit(0);
  }
 }
}