C++两栈共享空间

DouStack：

//两栈共享空间
#include<iostream>
using namespace std;
typedef int ElemType;
#define MAXSIZE 20

struct DouStack
{
    ElemType data[MAXSIZE];
    int top1;
    int top2;
};

void InitStack(DouStack *S)
{
    S->top1 = -1;
    S->top2 = MAXSIZE;
}

void ClearStack(DouStack *S)
{
    S->top1 = -1;
    S->top2 = MAXSIZE;
}

bool IsEmpty(DouStack *S)
{
    if(S->top1==-1 && S->top2==MAXSIZE)
    {
        cout<<"栈为空！"<<endl;
        return true;
    }
    else
    {
        cout<<"栈为空！"<<endl;
        return false;
    }
}

int LengthStack(DouStack *S)
{
    return (S->top1+1)+(MAXSIZE-S->top2);
}

void Push(DouStack *S, ElemType *e, int stackNumber)
{
    if(S->top1+1 == S->top2)
        cout<<"栈已满！"<<endl;
    if(stackNumber==1)
        S->data[++S->top1] = *e;
    else if(stackNumber==2)
        S->data[--S->top2] = *e;
}

void Pop(DouStack *S, ElemType *e, int stackNumber)
{
    if(stackNumber==1)
    {
        if(S->top1==-1)
                cout<<"栈1已空！"<<endl;
        *e = S->data[S->top1--];
    }
    else if(stackNumber==2)
    {
        if(S->top2==MAXSIZE)
                cout<<"栈2已空！"<<endl;
        *e = S->data[S->top2++];
    }
}

void PrintStack(DouStack *S)
{
    int i = -1;
    while(i<S->top1)
    {
        cout<<S->data[++i]<<" ";
    }
    i = S->top2;
    while(i<MAXSIZE)
    {
        cout<<S->data[i++]<<" ";
    }
    cout<<endl;
}

int main()
{
    DouStack S;
    int e;
    InitStack(&S);
    for(int i=1; i<=5; i++)
        Push(&S, &i, 1);
    PrintStack(&S);
    for(int i=MAXSIZE; i>=MAXSIZE-2; i--)
        Push(&S, &i, 2);
    PrintStack(&S);
    cout<<LengthStack(&S)<<endl;

    Pop(&S,&e,2);
    cout<<"弹出2的栈顶元素为："<<e<<endl;
    IsEmpty(&S);
    Pop(&S,&e,1);
    cout<<"弹出1的栈顶元素为："<<e<<endl;
    for(int i=6; i<=MAXSIZE-2; i++)
        Push(&S,&i,1);
    PrintStack(&S);

    ClearStack(&S);
    cout<<LengthStack(&S)<<endl;
    IsEmpty(&S);

    return 0;
}