Implementation of Queue using array in C Programming

#include< stdio.h>
#include< conio.h>
#define MAX 3
void main()
{
 int Q[MAX],f=-1,r=-1,ch,val,i;
 char cho='y';
 clrscr();
 while(cho=='y' || cho=='Y')
 {
  printf("\n1.Insert \n2.Delete \n3.Show \n4.Exit ");
  printf("\n Enter your choice:");
  scanf("%d",&ch);
  switch(ch)
  {
  case 1:
   if(r>=(MAX-1))
   {
    printf("\n Queue overflow");
   }
   else
   {
    printf("\n Enter value:");
    scanf("%d",&val);
    r++;
    Q[r]=val;

    if(f==-1)
    {
     f=f+1;
    }
   }
   break;
   case 2:
    if(f==-1)
    {
     printf("\n Queue underflow");
    }
    else
    {

     val=Q[f];
     printf("\n Deleted element is:%d",val);

     if(f==r)
     {
      f=-1;
      r=-1;
     }
     else
      f++;
    }
   break;
   case 3:
    if(f==-1)
    {
     printf("\n Queue empty");
    }
    else
    {
     printf("\n content of queue:\n");
     for(i=f;i<= r;i++)
     {
      printf("\t  %d",Q[i]);
     }
    }
   break;
  case 4:
   exit(0);
  }
       }
getch();
}

OUTPUT

1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:2

 Queue underflow
1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:1

 Enter value:11

1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:1

 Enter value:22

1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:1

 Enter value:33

1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:1

 Queue overflow
1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:3

 content of queue:
          11      22      33
1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:2

 Deleted element is:11
1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:2

 Deleted element is:22
1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:2

 Deleted element is:33
1.Insert
2.Delete
3.Show
4.Exit
 Enter your choice:2

 Queue underflow