c++ - C++ 中的链表、多项式、重载运算符 << 和 >>

Question

我必须构建一个从类 lista(列表)继承的类多项式(polinom)。我必须从多项式类中加、减、乘、除 2 个对象。我有这段代码。我不明白为什么我的析构函数不工作。我还必须重载运算符:+、-、<<、>> 但我不知道该怎么做。

#include <iostream>
#include <conio.h>

using namespace std;

struct nod
{float coef;
 int grad;
 nod* adr_urm;
};

class lista
{ 
public:
   nod *vf,*sf;
   lista();
   nod* adaug(nod *&vf,nod*& sf , int gr,float cf);
   void afis(nod* vz); 
   ~lista();
};

class polinom : public lista
{public:
polinom();
~polinom();

};




void lista::afis(nod* vz)
{nod *c=vz;
cout<<"Elementele polinomului"<<endl;
int i=0;
while (c)

 {if (i) cout<<"+";
 cout<<c->coef<<"X^"<<c->grad;
 c=c->adr_urm;
 i++;
 }
 cout<<endl<<endl;
}

nod* lista::adaug(nod *&vf,nod*& sf ,int gr,float cf)
{ nod *c=new nod;
c->coef=cf;
c->grad=gr;
c->adr_urm=0;
if (vf==0) vf=sf=c;
else {sf->adr_urm=c;
      sf=c;}
return vf;
}

lista::lista()
{vf=0;
}

polinom::polinom()
{vf=0;
}

lista::~lista()
{nod *m=vf, *m1=vf->adr_urm;
 while (m1)
       {delete m;
       m=m1;
       m1=m->adr_urm;
       }
 vf=0;
}

polinom::~polinom()
{nod *man=vf, *man1=vf->adr_urm;
 while (man1)
       {delete man;
       man=man1;
       man1=man->adr_urm;
       }
 vf=NULL;
}




int main()
{
int m,nr,nr1;
float n;
nod* vf=0 ;nod *sf;
nod* varFl=0 ;nod *varFv=0;

polinom l,v;

cout<<"Nr de elemente primul pol nr= ";
cin>>nr;
for (int i=1;i<=nr;i++)
{   cout<<"Elementul "<<i<<endl;
    cout<<"Coeficientul = ";
    cin>>n;
    cout<<"Gradul = ";
    cin>>m;
    l.adaug(vf,sf,m,n);
    varFl=vf;
}
l.afis(varFl);

vf=0;

cout<<"Nr de elemente al doilea pol nr= ";
cin>>nr1;
for (int j=1;j<=nr1;j++)
{cout<<"Elementul "<<j<<endl;
cout<<"Coeficientul = ";
cin>>n;
cout<<"Gradul = ";
cin>>m;
v.adaug(vf,sf,m,n);
varFv=vf;
}
v.afis(varFv);

l.~polinom();
v.~polinom();
_getch();


}

Answer 1

您的析构函数可能运行良好，但您调用了两次，第二次调用可能会导致段错误。像这样挂断电话

l.~polinom()

来自您的代码；自动调用析构函数。

第二，你不需要在polinom中复制lista析构函数；基类的析构函数也会自动调用。