堆栈——链式存储

定义

typedef struct SNode *PtrToSNode;
struct SNode {
	ElementType Data;
	PtrToSNode Next;
};
typedef PtrToSNode Stack;

建立堆栈

Stack CreateStack( ) {
	/* 构建一个堆栈的头结点，返回该结点指针 */
	Stack S;

	S = (Stack)malloc(sizeof(struct SNode));
	S->Next = NULL;
	return S;
}

判空

bool IsEmpty ( Stack S ) {
	/* 判断堆栈S是否为空，若是返回true；否则返回false */
	return ( S->Next == NULL );
}

压入

bool Push( Stack S, ElementType X ) {
	/* 将元素X压入堆栈S */
	PtrToSNode TmpCell;

	TmpCell = (PtrToSNode)malloc(sizeof(struct SNode));
	TmpCell->Data = X;
	TmpCell->Next = S->Next;
	S->Next = TmpCell;
	return true;
}

弹出

ElementType Pop( Stack S ) {
	/* 删除并返回堆栈S的栈顶元素 */
	PtrToSNode FirstCell;
	ElementType TopElem;

	if( IsEmpty(S) ) {
		printf("堆栈空");
		return ERROR;
	} else {
		FirstCell = S->Next;
		TopElem = FirstCell->Data;
		S->Next = FirstCell->Next;
		free(FirstCell);
		return TopElem;
	}
}