is this a design flaw

hey (prelude, most likely ;) ) all, if you have a sec can you check the attached. i pulled them nearly verbatium from a book. i don't know if i'm missing something or the book messed up. thanks in advance.

here's the header

i think it is, if anyone cares. i made this modifaction:

Code:

---

void c_stack::mf_peek(void)
{
        if (back!=0)
        {
                cout<<endl<<"this is your character: "<<data[back-1]<<endl; //[back-1] is the change
        }
        else
        {
                cout<<endl<<"stack is empty"<<endl;
        }
}

---

what's another way to solve it?

I just looked over it really quick (I hit the hay soon). I noticed you make a call to exit(). You have to include stdlib.h or cstdlib to be able to use that.

it exits fine without, i'm using bcc55. maybe they have a different library

Yep, that sure is an error. Most likely caused by a lack of error handling so as to keep the code small for the book. I personally would have added more checking, that out of bounds value is ugly ;)
You can fix the problem with a simple test before printing.

Code:

---

void c_stack::mf_peek(void)
{
  if (back!=0)
  {
    cout<<endl<<data[back]<<endl;
  }
  else
  {
    cout<<endl<<"stack is empty"<<endl;
  }
}

---

to

Code:

---

void c_stack::mf_peek(void)
{
  if (back!=0)
  {
    if ( back >= 9 )
      cout<<endl<<data[back-1]<<endl;
    else
      cout<<endl<<data[back]<<endl;
  }
  else
  {
    cout<<endl<<"stack is empty"<<endl;
  }
}

---

Though technically, you could keep the size the same by sacrificing readability in the test using the ternary operator in cout, which I don't recommend unless you document it very well.

Code:

---

cout<<endl<<data[( back >= 9 )?back-1:back]<<endl;

---

Also, to be able to use exit() safely you must include stdlib.h or cstdlib, your author seems to have forgotten that.

-Prelude