Find middle element of stack by R4R Team

program-

#include< stdio.h>
#include< conio.h>
#include< alloc.h>
struct stack
{
int data;
struct stack *back;
};
struct stack *top;

void create()
{
char ch;
struct stack *ptr,*cpt;
printf("Enter Number\n");
cpt=(struct node*)malloc(sizeof(struct stack));
scanf("%d",&cpt->data);
cpt->back=NULL;
do
{
printf("Enter Number\n");
ptr=(struct stack*)malloc(sizeof(struct stack));
scanf("%d",&ptr->data);
ptr->back=cpt;
cpt=ptr;
printf("Continue(y/n)?\n");
ch=getch();
}while(ch=='y');
top=cpt;
}

void traverse()
{
struct stack *ptr=top;
printf("Stack is :\n");
while(ptr!=NULL)
{
printf("%d ",ptr->data);
ptr=ptr->back;
}
}

void middle()
{
struct stack *ptr=top;
int len=0,i;
while(ptr!=NULL)
{
len++;
ptr=ptr->back;
}
ptr=top
for(i=0;i< =len/2;i++)
{
ptr=ptr->back;
}
printf("Middle element of stack is %d",ptr->data);
}

void main()
{
clrscr();
create();
traverse();
middle();
getch();
}

Enter Number
3
Enter Number
4
Continue(y/n)?
Enter Number
7
Continue(y/n)?
Enter Number
1
Continue(y/n)?
Enter Number
6
Continue(y/n)?
Stack is :
6 1 7 4 3
Middle element of stack is 7