雙指針不帶頭結點的鏈棧的實現（C語言）

/*
	雙指針 不帶頭結點的鏈棧
	VS2010 調試
*/
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>

#define TRUE 1
#define FALSE 0
#define ERROR -1
#define OK 1

struct Node
{
	int data;
	struct Node *next;
};

struct LStack
{
	struct Node *top;
	struct Node *base;
};

//棧初始化
void init_stack(struct LStack *linkStack)
{

	linkStack->base = NULL;
	linkStack->top = NULL;
}

//判斷棧是否爲空
int is_stack_empty(struct LStack *linkStack)
{

	return ((linkStack->base == NULL) ? TRUE : FALSE);
}

//進棧，數num進棧
int push_stack(struct LStack *linkStack, int num)
{
	struct Node *tmp_node = (struct Node *)malloc(sizeof(struct Node));
	if(tmp_node == NULL)
	{
		return ERROR;
	}
	tmp_node->data = num;
	tmp_node->next = NULL;

	if(is_stack_empty(linkStack))
	{
		linkStack->base = tmp_node;
		linkStack->top = tmp_node;
	}
	else
	{
		tmp_node->next = linkStack->top;
		linkStack->top = tmp_node;
	}
	
	return OK;
}

//出棧，出棧元素保存在num中
int pop_stack(struct LStack *linkStack, int *num)
{
	struct Node *tmp_node = NULL;

	if(is_stack_empty(linkStack))
	{
		return ERROR;
	}

	*num = linkStack->top->data;
	tmp_node = linkStack->top;
	linkStack->top = linkStack->top->next;

	if(linkStack->top == NULL)
	{
		linkStack->base = NULL;
	}
	free(tmp_node);

	return OK;
}

//或取棧頂元素，放入num中
int get_head_elem(struct LStack linkStack, int *num)
{
	if(is_stack_empty(&linkStack))
	{
		return ERROR;
	}

	*num = linkStack.top->data;

	return OK;
}

//銷燬棧
int destory_stack(struct LStack *linkStack)
{
	struct Node *tmp_node = NULL;

	if(is_stack_empty(linkStack))
	{
		return OK;
	}

	while(linkStack->top != NULL)
	{
		tmp_node = linkStack->top;
		linkStack->top = linkStack->top->next;
		free(tmp_node);
	}

	linkStack->base = NULL;

	return OK;
}

//獲取棧的長度，將長度返回
int get_stack_length(struct LStack linkStack)
{
	int length = 0;

	if(is_stack_empty(&linkStack))
	{
		return 0;
	}

	while (linkStack.top != NULL)
	{
		linkStack.top = linkStack.top->next;
		length++;
	}
	return length;
}

//打印棧內的數據元素
void print_stack(struct LStack linkStack)
{
	printf("TOP\n");
	while(linkStack.top != NULL)
	{
		printf("%d\n", linkStack.top->data);
		linkStack.top = linkStack.top->next;
	}
	printf("BOTTOM\n\n");
}

int main(int argc, char *argv[])
{
	int num = 0;
	struct LStack linkStack;
	init_stack(&linkStack);

	push_stack(&linkStack, 7);
	push_stack(&linkStack, 8);
	push_stack(&linkStack, 9);
	push_stack(&linkStack, 6);
	push_stack(&linkStack, 5);
	print_stack(linkStack);

	pop_stack(&linkStack, &num);
	print_stack(linkStack);

	get_head_elem(linkStack, &num);
	printf("%d,%d\n", get_stack_length(linkStack), num);

	destory_stack(&linkStack);

	return 0;
}