implementation of stacks using linked lists in c++

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
struct node{
    int data;
    struct node *link;
    };
    struct node *top=NULL,*temp;
    void main(){
    int choice,data; 
    clrscr();  
    while(1){
    printf("\n1.Push\n2.Pop\n3.Display\n4.Exit\n");
    printf("\nEnter ur choice:");    
    scanf("%d",&choice);   
    switch(choice){  
        case 1:  
        temp=(struct node *)malloc(sizeof(struct node)); 
        printf("Enter a node data :"); 
        scanf("%d",&data); 
        temp->data=data;  
        temp->link=top; 
        top=temp;   
        break;    
        case 2:   
        if(top!=NULL){
        printf("The poped element is %d",top->data); 
        top=top->link; 
        }          
        else{
        printf("\nStack Underflow");
        }
        break;
        case 3:
        temp=top;
        if(temp==NULL){
        printf("\nStack is empty\n");
        }
        while(temp!=NULL){
        printf("->%d->",temp->data);
        temp=temp->link;
        }
        break;
        case 4:
        exit(0);
        }
      }
    }

#include<stdio.h>
#include<malloc.h>

#define maxsize 10
void push();
void pop();
void display();

struct node{
int info;
struct node *link;
}
*start=NULL, *new,*temp,*p;
typedef struct node N;
main(){
int ch,a;
do{
printf("\t\t\tLinked stack");
printf("\n 1.Push");
printf("\n 2.Pop");
printf("\n 3.Display");
printf("\n 4.Exit");
printf("\n Enter your choice : ");
scanf("%d",&ch);
switch(ch){
case 1:
push();
break;

case 2:
pop();
break;

case 3:
display();
break;

case 4:
exit(0);
default:

printf("\nInvalid choice");
break;
}
}
while(ch<=3);
}
void push(){
new=(N*)malloc(sizeof(N));
printf("\nEnter the item : ");
scanf("%d",&new->info);
new->link=NULL;
if(start==NULL)
start=new;
else{
p=start;
while(p->link!=NULL)
p=p->link;
p->link=new;
}
}
void pop(){
if(start==NULL)
printf("\nStack is empty");
else if(start->link==NULL){
printf("\nThe deleted element is : %d",start->info);
free(start);
start=NULL;
}
else{
p=start;
while(p->link!=NULL){
temp=p;
p=p->link;
}
printf("\nDeleted element is : %d\n", p->info);
temp->link=NULL;
free(p);
}
}
void display(){
if(start==NULL)
printf("\nStack is empty");
else{
printf("\nThe elements are : ");
p=start;
while(p!=NULL){
printf("%d",p->info);
p=p->link;
}
printf("\n");
}
}