# Stack Pop, Push, Peek...

I just learnt how to use the Stack today, and I was wondering if anyone has a practical use for the stack.  I can only think of trivial uses for it like I wrote a program that reverses a string using the old PushPop method.  But can anyone give me some examples of how it could be used in the real world???

Tim
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Commented:
I'm currently writing a chess program.  In a chess program, it's necessary to traverse a tree of possible moves and apply a Minimax algorithm to assess the position scores at the terminal nodes.  Eventually, you  have to back those scores back up to the root node and choose the move that gives the highest score.

The list of moves made as you traverse the tree is stored in a stack.  The move is made on the board object and the move is pushed onto the stack.  This goes on for a while.  Eventually, you will want to unmake the moves to go back towards the starting position. To do this you pop the move off the stack and unmake that move on the board object.  So the stack represents the path or move list from the initial position to the current position being evaluated.

My particular application is a chess program, but I'm certain a stack is useful in other tree traversal applications.
Commented:
another real use of a STACK is to be able to UNDO a set of opertations.  As each operation is to be performed, that state of what it is to work on is PUSHED onto the Stack.  If you then wish to UNDO the last operation, then the stack is POPPED, and the last operation is un-done.  To undo a set of operations, the stack is POPPED multiple times, to undo each step in the reverse of the order in which they were originally done.

AW

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