C++ 作业 (双向栈)

/*
   author
   screen  name   Andromeda_Galaxy;
   chinese name   杨子俊
*/
#include<bits/stdc++.h>
using namespace std;
struct position
{
    int date=0;
    position *next;
    position *before;
};
struct  qstack
{
    position p;  // front;
    position q;  // rear;
};
void build(qstack &s)
{
    s.q.date=0;
    s.q.before=NULL;
    s.q.next=&s.q;
    s.p.date=0;
    s.p.before=&s.q;
    s.p.next=NULL;
}
void make_stack(qstack &s,int x,int num)
{
    if(x==1)
    {
        cout<<"前端插入元素  "<<num<<endl;
        position *x1=s.p.before;
        (*x1).next=new position;
        position *x2=(*x1).next;
        (*x2).date=num;
        (*x1).next=x2;
        (*x2).before=x1;
        (*x2).next=&s.p;
         s.p.before=x2;
    }
    else
    {
        cout<<"后端插入元素  "<<num<<endl;
        position *x1=s.q.next;
        (*x1).before=new position;
        position *x2=(*x1).before;
        (*x2).date=num;
        (*x1).before=x2;
        (*x2).next=x1;
        (*x2).before=&s.q;
        s.q.next=x2;
    }
}
void p_stack(qstack &s,int x)
{
    if(x==1)
    {

        position *x2=s.p.before;
        cout<<"前端删除元素  "<<(*x2).date<<"  "<<endl;
        position *x1=(*x2).before;
        (*x1).next=&s.p;
        s.p.before=x1;
        delete(x2);
    }
    else
    {
        position *x2=s.q.next;
        cout<<"后端删除元素  "<<(*x2).date<<"  "<<endl;
        position *x1=(*x2).next;
        (*x1).before=&s.p;
        s.q.next=x1;
        delete(x2);
    }
}
void ffind(qstack &s,int x)
{
    position *x2=&s.p;
    if(s.q.next==x2)
    {
        cout<<"error"<<endl;
        return ;
    }
    if(x==1)
    {
        position x1=*s.p.before;
        cout<<"查询前端元素  "<<x1.date<<endl;
    }
    else
    {
        position x1=*s.q.next;
        cout<<"查询后端元素  "<<x1.date<<endl;
    }
}
int main()
{
    qstack s; cout<<"make s"<<endl;
    build(s); cout<<"build s"<<endl;
    make_stack(s,1,10);
    make_stack(s,1,100);// cout<<"make_stack OK"<<endl;
cout<<"-------------------"<<endl;
    ffind(s,1);
    ffind(s,0);
cout<<"-------------------"<<endl;
    make_stack(s,0,1);
    make_stack(s,0,2);
cout<<"-------------------"<<endl;
    ffind(s,1);
    ffind(s,0);
cout<<"-------------------"<<endl;
    p_stack(s,1);
    p_stack(s,0);
cout<<"-------------------"<<endl;
    ffind(s,1);
    ffind(s,0);
cout<<"-------------------"<<endl;
    p_stack(s,1);
    p_stack(s,0);
cout<<"-------------------"<<endl;
    ffind(s,1);
}