数据结构（三）：堆栈

1、元素定义

typedef int STDataType;
typedef struct Stack
{
	STDataType* a;
	int top;
	int capacity;
}ST;

2、接口函数

//堆栈初始化
void StackInit(ST* ps);
//销毁栈
void StackDestory(ST* ps);
//入栈
void StackPush(ST* ps, STDataType x);
//出栈
void StackPop(ST* ps);
//获取栈顶数据
STDataType StackTop(ST* ps);
//栈数据个数
int StackSize(ST* ps);
//判断是否为空栈
bool StackEmpty(ST* ps);

2.1堆栈初始化

void StackInit(ST* ps)
{
	assert(ps);
	ps->a = NULL;
	ps->top = 0;//top=0,指向栈顶数据的下一个
	ps->capacity = 0;
}

2.2销毁栈

void StackDestory(ST* ps)
{
	assert(ps);
	free(ps->a);
	ps->a = NULL;
	ps->top = ps->capacity = 0;
}

2.3入栈

void StackPush(ST* ps, STDataType x)
{
	assert(ps);
	if (ps->top == ps->capacity)//栈存满扩容
	{
		int newCapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
		STDataType* tmp = realloc(ps->a, sizeof(STDataType) * newCapacity);
		if (tmp == NULL)
		{
			printf("realloc fail\n");
			exit(-1);
		}
		ps->a = tmp;
		ps->capacity = newCapacity;
	}
	ps->a[ps->top] = x;
	ps->top++;
}

2.4出栈

void StackPop(ST* ps)
{
	assert(ps);
	assert(!StackEmpty(ps));
	//assert(ps->top > 0);
	ps->top--;
}

2.5获取栈顶数据

STDataType StackTop(ST* ps)
{
	assert(ps);
	//assert(ps->top > 0);
	assert(!StackEmpty(ps));
	return ps->a[ps->top - 1];
}

2.6栈存放数据数量

int StackSize(ST* ps)
{
	assert(ps);
	return ps->top;
}

2.7判断空栈

bool StackEmpty(ST* ps)
{
	assert(ps);
	return ps->top == 0;
}