栈

定义

  • 一种可以实现“先进后出”的存储结构，栈类似箱子

分类

  1. 静态栈
  2. 动态栈

算法

  1. 出栈
  2. 压栈

应用

  1. 函数调用
  2. 中断
  3. 表达式求值
  4. 内存分配
  5. 缓冲处理
  6. 迷宫

代码

//stack.cpp  

#include <stdio.h>
#include <malloc.h>  
#include <stdlib.h>  

typedef struct Node
{
    int data;
    struct Node * pNext;
}NODE, *PNODE;

typedef struct Stack
{
    PNODE pTop;
    PNODE pBottom;
}STACK, *PSTACK;

//函数声明
void init(PSTACK);
void push(PSTACK, int);
void traverse(PSTACK);
bool pop(PSTACK, int *);
void clear(PSTACK);

int main(void)
{
    STACK S;            //STACK等价于struct Stack
    int val;

    init(&S);           //目的是造出一个空栈
    push(&S,1);
    push(&S,2);
    clear(&S);

    if( pop(&S, &val) )
    {
        printf("%d \n", val);
    }
    else
    {
        printf("shibia");
    }
    
    traverse(&S);
    clear(&S);
    traverse(&S);

    system("PAUSE");
    return 0;
}

void init(PSTACK pS)
{
    pS->pTop = (PNODE)malloc( sizeof(NODE) );
    if(NULL == pS->pTop)
    {
        printf("动态内存分配失败！\n");
        exit(-1);
    }
    else
    {
        pS->pBottom = pS->pTop;
        pS->pTop->pNext = NULL;  //等价于 pS->pBottom->pNext = NULL;
    }
    
}

void push(PSTACK pS, int val)
{
    PNODE pNew = (PNODE)malloc( sizeof(NODE) );

    pNew->data = val;
    pNew->pNext = pS->pTop;
    pS->pTop = pNew;

    return;
}

void traverse(PSTACK pS)
{
    PNODE p = pS->pTop;

    while(p != pS->pBottom)
    {
        printf("%d ", p->data);
        p = p->pNext;
    }
    printf("\n");

    return;
}

bool empty(PSTACK pS)
{
    if(pS->pTop == pS->pBottom)
    return true;
    else
    {
        return false;
    }
    
}

bool pop(PSTACK pS, int * pVal)
{
    if( empty(pS) )
    {
        return false;
    }
    else
    {
        PNODE r = pS->pTop;
        *pVal = r->data;
        pS->pTop = r->pNext;
        free(r);
        r = NULL;

        return true;
    }
    
}

void clear(PSTACK pS)
{
    if( empty(pS) )
    return;
    else
    {
        PNODE p = pS->pTop;
        PNODE q = NULL;

        while(p != pS->pBottom)
        {
            q = p->pNext;
            free(p);
            p = q;
        }
        pS->pTop = pS->pBottom;
    }
}