Stacks

Stacks are declared as an "abstract" class. They are currently implemented in any of three ways.

VStack

implement fixed sized stacks via arrays.

XPStack

implement dynamically-sized stacks via XPlexes.

SLStack

implement dynamically-size stacks via linked lists.

All possess the same capabilities. They differ only in constructors. VStack constructors require a fixed maximum capacity argument. XPStack constructors optionally take a chunk size argument. SLStack constructors take no argument.

Assume the declaration of a base element x.

Stack s; or Stack s(int capacity)

declares a Stack.

s.empty()

returns true if stack s is empty.

s.full()

returns true if stack s is full. XPStacks and SLStacks never become full.

s.length()

returns the current number of elements in the stack.

s.push(x)

pushes x on stack s.

x = s.pop()

pops and returns the top of stack

s.top()

returns a reference to the top of stack.

s.del_top()

pops, but does not return the top of stack. When large items are held on the stack it is often a good idea to use top() to inspect and use the top of stack, followed by a del_top()

s.clear()

removes all elements from the stack.