进栈出栈初始化栈

* 栈的顺序存储结构

• 判断栈空的条件 ： s -> top == -1;

• 栈满的条件： s -> top == Maxsize - 1;（data 数组的最大下标）

• 进栈操作： s ->top ++; s ->data[s ->top] = x;无需再传参回到主函数

• 出栈操作：x = s ->data[s ->top];s -> top –;;需传参回到主函数**

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

#define Maxsize 50

typedef int Elemtype;

typedef struct
{
    Elemtype data[Maxsize];

    int top;
}Sqstruct;

//初始化栈
void Initstruct(Sqstruct*& s)
{
    s = (Sqstruct*)malloc(sizeof(Sqstruct));

    s->top = -1;//栈顶指针初始为-1
}

//进栈
bool pushstruct(Sqstruct*& s, Elemtype x)
{
    if (s->top == Maxsize - 1)//判断栈是否满
    {
        return false;
    }
    s->top++; //先让栈顶指针加一，在存放元素；
    s->data[s->top] = x;
    return true;
}


//出栈
bool popstruct(Sqstruct*& s, Elemtype& x)
{
    if (s->top == -1) //判断栈是否为空
    {
        return false;
    }
    x = s->data[s->top]; //先让栈顶元素出栈，再让栈顶指针减减；
    s->top--;
    return true;
}

*** 栈的链式存储结构

栈空 s ->next ==NULL;
栈满：在链式存储结构中可以不考虑
元素 进栈操作：1.p = malloc;2.p -> data =e;3.p -> next = s -> next ;4.s ->next =p;
取栈顶元素操作 : e = s -> next -> data,
出栈操作：1.判断栈是否为空(s -> next ==NULL) 2.p = s-> next;e = p -> data;s->next = p ->next;free(p)**

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

typedef int Elemtype;
typedef struct Linkedstack
{
    Elemtype data;
    struct Linkedstack* next;

}Ls;

//头插法建立栈
void Pushstack(Ls*& s, Elemtype e)
{
    Ls* p;
    p = (Ls*)malloc(sizeof(Ls));//申请空间用来存放结点
    p->data = e;

    p->next = s->next; //将 p 结点作为头结点插入
    s->next = p;
}

//从头结点开始删除一个元素
bool popstack(Ls*& s, Elemtype& e)
{
    Ls* p;
    if (s->next == NULL)
    {
        return false;
    }
    p = s->next;

    e = p->data;

    s->next = p->next;

    free(p);
    return true;
}

//取栈顶元素
bool getstack(Ls*& s, Elemtype& e)
{
    if (s->next == NULL)
    {
        return false;
    }
    e = s->next->data;//取出头结点
    return true;
}

括号的匹配

bool Flage(char a[],int n)
{
    int i =0;char e;
    bool flage = true;
    LS *st;
    InitStack(st);

    while (i < n && flage)
    {
        if(a[i] =='(' || a[i] == '{' || a[i] == '[')
            push(st,e[i]);

        if(a[i] == ')')
        {   
            if(Get(st,e))
            {    
                if(e =='(') pop(st,e);
                else flage =false;
            }
            flage = false;
        }
        if(a[i] =='}')
        {
            if(Get(st,e))
            {
                if(e == '{') pop(st,e);
                else flage = false;
            }
            flage = false;
        }
        if(a[i]==']')
        {
            if(GetTop(st,e))
            {
                if(e == '[') pop(st,e);
                else flage =false;
            }
            flage = false;
        }
        i ++;
    }
    if (!StackEmpty(st)) flage = false;
    DestoryStack(st);
    return flage;
}