DS stack 스택 자료구조 (C)

STACK

• stack is an ordered list in which insertions (push & add) and deletions (pop & remove) are made at on end called top
• Last-In-First-Out (LIFO)

ADT

• objects : a finite ordered list with zero or more elements
• functions :

Stack CreateS(maxStackSize)	create an empty stack whos maximum size if maxStackSize
Boolean IsFull(stack,maxStackSize)	if (number of elements in stack == maxStackSize) return TRUE else return FALSE
Stack Push(stack, item)	if (IsFull(stack)) stack full else insert item into top of stack and return
Boolean IsEmpty(stack)	if (stack == CreateS(maxStackSize)) return TRUE else return FALSE
Element Pop(stack)	if (IsEmpty(stack)) return else remove and return the element at th top of the stack

Push() & Pop()

보통 아래와 같은 형식으로 함수를 사용한다.

• push(item)
• item = pop()

void push(element item)
{
    if (top >= MAX_STACK_SIZE-1)  # 가득 차있으면 넣을 수 없음
        stackFull();
    stack[++top] = item;  # push를 하면 top += 1을 해줘야 함 (다음 element를 가리키게)
}

void pop()
{
    if (top < 0)				# 비어있다면 뺄 게 없음
        return stackEmpty();
    return stack[--top];		# 하나를 빼줬으니, top -= 1을 해줌!
}