The stack is used while evaluating arithmetic expressions so that a statement such as:
2 + 3 -> x;actually takes place in four steps, thus:
(1) Put 2 on the stack
(2) Put 3 on the stack
(3) Do the addition, that is remove the top two items on the stack
(ie 2 and 3) and replace them by their sum (ie 5)
(4) Remove the top item from the stack (ie 5) and put it in
the variable X.
A more complicated example, such as:
2 + 3 * 4 - 5 =>takes place in EIGHT steps, which are left as an exercise for the reader to describe, some of which are:
(4) Do a multiplication
(5) Do an addition
(7) Do a subtraction
(8) Print the contents of the stack