implementation of stack using array

/*Program : implementation of stack using array
Programmer ::fizmhd(MEA) www.mdown.co.cc*/

#include
void push(int);
int pop(void);
void display(void);

int main()
{
int choice=0,val=0;
do
{
printf("\n\t1.Push 2.Pop 3.Display 4.Exit\n\tSelect Your Choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1:
printf("\tElement to be Pushed : ");
scanf("%d",&val);
push(val);
break;
case 2:
val=pop();
if(val!=-1)
printf("\tPopped Element : %d\n",val);
break;
case 3:
display();
break;
case 4:
break;
default:
printf("\tWrong Choice");
break;
}
}while(choice!=4);
return 0;
}
#define maxsize 100
int stack[maxsize];
int stacktop=0;

void push(int val)
{
if(stacktopstack[stacktop++]=val;
else
printf("Stack Overflow");
}

int pop()
{
int a;
if(stacktop>0)
{
stacktop--;
a=stack[stacktop];

return a;
}
else
{
printf("Stack is Empty");
return -1;
}
}

void display()
{
int i=0;
if(stacktop>0)
{
printf("\tElements are:");
while(i{
printf("\t%d",stack[i++]);
}
printf("\n");
}

else
printf("\tStack is Empty\n");
}