stack program.

// Stack program in Data structure
#include  // include header file stdio.h
#include // include header file stdlib.h
int top=-1;

void main()
{
 int size,a[10],i,j;
 printf("Enter a size of stack :");
 scanf("%d",&size);
 system("clear");
 
      x:
 for(i=size-1; i>=0; i--)
 {
         printf("\n\t|");
  if(top>=i)
  {
    printf("%d|",a[i]);
  }
  else  
   printf("  |"); 
  if(i==top)
  {
     printf("<-top"); 
  }
 } 

 printf("\n\n1.push");
 printf("\n2.pop");
 printf("\n3.peep ");
 printf("\n4.update ");
 printf("\n\nEnter your choice : ");
 int n;
 scanf("%d",&n);
 
 if(n==1)
 {
  if(top==size-1)
  {
   printf("\n\nStack is over flow\n");
  }
  else
  {
   top++;
   printf("Entrer a value :");
   scanf("%d",&a[top]);
  }
 }
 if(n==2)
 {
  if(top>=0)
  {
   a[top]=0;
   top--;
  }
  else
  {
   printf("\n\n Stack is already empty \n\n");
  }
 }
 if(n==3)
 {
  printf("\nEnter a value : ");
  int c;  
  scanf("%d",&c);
  if(c>0 && c<=top+1)
  {
   printf("%d",a[top+1-c]);
  }
 }
 if(n==4) 
 {
  printf("\nEnter a possition : ");
  int c;  
  scanf("%d",&c);
  printf("\nEnter a value to update : ");
  int u;
  scanf("%d",&u);
  if(c>0 && c<=top+1)
  {
   a[top+1-c]=u;
  }
 }
 
 printf("\n\nDo you want to continue than tap 1 :");
 int b;
 scanf("%d",&b);
 if(b==1)
 {
  int x;
  goto x;
 }
}

 |  |
 |  |
 |  |
 |  |
 |  |

1.push
2.pop
3.peep 
4.update 

Enter your choice : 1
Entrer a value :34


Do you want to continue than tap 1 :1

 |  |
 |  |
 |  |
 |  |
 |34|<-top

1.push
2.pop
3.peep 
4.update 

Enter your choice :