WAP of STACK

/*WAP of STACK*/

#include<stdio.h>
#include<conio.h>
#include<alloc.h>
#include<process.h>
struct stack
{
  int no;
  struct stack *next;
}*top=NULL;
typedef struct stack st;
void push();
int pop();
void display();
void main()
{
    char ch = 'y';
    int choice,temp;
    clrscr();
    do
    {

      printf("\n1:push");
      printf("\n2:pop");
      printf("\n3:display");
      printf("\n4:exit");
      printf("\nEnter your choice");
      scanf("%d",&choice);
      switch(choice)
      {
        case 1:push();
             break;
        case 2:temp=pop();
        printf("the deleted element is%d",temp);
             break;
        case 3:
             display();
             break;
       case 4:
             exit(0);
             break;
        default:
             printf("\n wrong choice");
      }
      printf("do you want continue(y/n)");
      flushall();
      scanf("%c",&ch);
    }
    while(ch =='Y'|| ch =='y');
 }
 void push()
 {

    st*P;
    P=(st*)malloc(sizeof(st));
    printf("\nthe number");
    scanf("%d",&P->no);
    P->next=top;
    top=P;
 }
    int pop()
    {
       st*P;
       P=top;
       if(top==NULL)
       {
           printf("stack is already empty");
           getch();
           exit(0);
       }
       else
       {
           top=top->next;
           free(P);
       }
       return(P->no);
    }
    void display()
    {

       st*P;
       P=top;
       while(P->next != NULL)
       {
            printf("\n=%d",P->no);
            P=P->next;
       }
       printf("\nno=%d",P->no);
    }

---

How to earn online:

1. 
   Step - 1 :
   
   signup for PayPal, to recieve your online earning
   click here:
   https://www.paypal.com/in/mrb/pal=CZ7224TZBMCBL
2. 
   step - 2 :
   Read & Rate interesting articales to earn money!
   per artical $0.03 to $0.10
   link: http://www.readbud.com/?ref=4096068
3. 
   EARN MONEY BY BUMPING SITES, DAILY 5 ADS TO CLICK,
   PER CLICK 0.02$, DAILY 0.10$ EARN, MINIMUM PAYOUT 15$,
   YES ITS FREE TO JOIN
   http://www.MoneyBumper.com/Main.cfm?R=134526