Accessing elements in a stack?

[scuba6388]

I need to be able to access and move elements within a stack (C++ STL). I have tried using an iterator to navigate to the element that I want to move, but then I realized that I don't know how to remove that element. Is there a way to use pop to remove the element that my iterator is pointing to? Can you even use iterators on a stack? I'm kind of lost. Any help would be greatly appreciated.

[weaknessforcats]

A stack is a LIFO queue (last-in-first-out) so there is no provision to access members of the stack or move them around.

That is done using a vector.

[scuba6388]

A stack is a LIFO queue (last-in-first-out) so there is no provision to access members of the stack or move them around.

That is done using a vector.

Thats kind of what I thought, but the homework question reads: part a

"Write a function

 template <typename T>
T second(const stack<T>& s);

that uses stack operations to return the second element on the stack."

For this part I just popped to T temp then used top( ) then push(temp) and I output the value that I got from top( )

But for part b:

Write a function

 template <typename T>
void n2top(stack<T>& s, int n);

that moves the nth element (counting from the top, which is element 1) of the stack to the top, leaving the order of all other elements unchanged.

So I'm still not really sure what its looking for.

[Laharl]

Are you allowed to use a second stack and/or temporary variables? If so, consider how you could store the order and the value you seek using them.

[weaknessforcats]

Oh, I see now. An academic exercise.

To see the nth element of a stack,

1) pop all the elements before n and push them into a second stack.
2) do a top() to see the value of the nth element
3) push all of the elements from the second stack back onto the first stack.
4) delete the second stack

[scuba6388]

thanks everyone, I figured it out before the previous post, but that just confirms it. It seems like a stupid question now that I figured it out, so thanks everyone for your help.

[Ganon11]

thanks everyone, I figured it out before the previous post, but that just confirms it. It seems like a stupid question now that I figured it out, so thanks everyone for your help.

It's not a stupid question, it just requires a little thinking about how stacks work and how you might be able to use them.