两个栈共享同一存储空间

#include <iostream>using namespace std;const int StackSize = 100;class BothStack{private:    int data[StackSize];  ///存放两个栈的数组    int top1, top2; ///两个栈的栈顶指针，分别为各自栈顶元素在数组中的下标public:    BothStack() {        top1 = -1;        top2 = StackSize;    }  ///构造函数，将两个栈分别初始化    ~BothStack() {} ///析构函数为空    void Push(int i, int x); //入栈操作，将元素x压入栈i    int Pop(int i);  ///出栈操作，对栈i执行出栈操作）    int Empty(int i) {        if (top1 == -1 && top2 == StackSize)            return 1;        else            return 0;    }  ///判断栈是否为空};void BothStack::Push(int i, int x) ///入栈操作，将元素x入栈{    if (top1 == top2 - 1)  throw "上溢"; ///判断是否栈满    if (i == 1)  data[++top1] = x; ///在栈1中插入    if (i == 2)  data[--top2] = x; ///在栈2中插入}int BothStack::Pop(int i)  ///出栈操作，将栈顶元素弹出{    if (i == 1) { ///在栈1中删除        if (top1 == -1) ///判断栈1是否为空            throw "下溢";        return data[top1--];    }    if (i == 2) { ///在栈2中删除        if (top2 == StackSize) ///判断栈2是否为空            throw "下溢";        return data[top2++];    }}int main(){BothStack B;B.Push(1,1);B.Push(2,2);B.Push(1,3);B.Push(2,4);cout << B.Pop(1) <<endl;cout << B.Pop(1) <<endl;cout << B.Empty(1) <<endl;    return 0;}