【发布时间】：2016-02-07 00:05:30
【问题描述】：
我有以下代码：
问题是当我在 main 类型中创建一个列表时：Reteta。
显示列表后，我收到错误分配错误。如果我从 Reteta 类中评论析构函数，程序就可以工作。你能帮我找出错误吗？或者也许我没有很好地显示列表，所以程序还有其他问题需要处理。
代码如下：
#include<iostream>
#include<fstream>
#include<list>
using namespace std;
class Medicament{
private:
char *denumire;
float pret;
public:
Medicament()
{
this->pret = 0;
this->denumire = new char[strlen("Fara denumire")];
strcpy(this->denumire, "Fara denumire");
}
Medicament(char* denumire, float pret)
{
this->denumire = new char[strlen(denumire) + 1];
strcpy(this->denumire, denumire);
this->pret = pret;
}
Medicament(const Medicament& x)
{
this->denumire = new char[strlen(x.denumire) + 1];
strcpy(this->denumire, x.denumire);
this->pret = x.pret;
}
~Medicament()
{
if (this->denumire)
{
delete[] this->denumire;
}
}
void setDenumire(char *x)
{
if (x)
{
if (this->denumire)
{
delete[] this->denumire;
}
this->denumire = new char[strlen(x) + 1];
strcpy(this->denumire, x);
}
}
char* getDenumire()
{
return this->denumire;
}
void setPret(float f)
{
if (f)
{
this->pret = f;
}
}
Medicament operator=(Medicament x)
{
this->denumire = new char[strlen(x.denumire) + 1];
strcpy(this->denumire, x.denumire);
this->pret = x.pret;
return *this;
}
friend ostream& operator<<(ostream& consola, Medicament &x)
{
consola << "Medicament: " << x.denumire << endl; //error here
consola << "Pret: " << x.pret << endl;
return consola;
}
float getPret()
{
return this->pret;
}
friend class Reteta;
};
class Reteta{
protected:
Medicament *medicamente;
int n;
public:
Reteta()
{
this->n = 0;
this->medicamente = NULL;
}
Reteta(Medicament *v, int n)
{
this->n = n;
this->medicamente = new Medicament[n];
for (int i = 0; i < n; i++)
{
this->medicamente[i] = v[i];
}
}
~Reteta()
{
if (this->medicamente)
{
delete[] this->medicamente; //The problem is here. If I comment this the program works.
}
}
int getN()
{
return this->n;
}
friend ostream& operator<<(ostream& consola, Reteta& x)
{
consola << "Numar de medicamente: " << x.n << endl;
consola << " -->Lista Medicamente<-- "<<endl;
for (int i = 0; i < x.n; i++)
{
consola << x.medicamente[i].getDenumire() <<endl; //error at this line when I compile
consola << x.medicamente[i].getPret()<< endl;
}
return consola;
}
void adaugaMedicament(Medicament x)
{
Reteta y;
y.medicamente= new Medicament[this->n+1];
for (int i = 0; i < this->n; i++)
{
y.medicamente[i] = this->medicamente[i];
}
y.medicamente[this->n] = x;
delete[] this->medicamente;
this->medicamente = new Medicament[this->n + 1];
this->n++;
for (int i = 0; i < this->n; i++)
{
this->medicamente[i] = y.medicamente[i];
}
}
Medicament operator[](int i)
{
if (i >= 0 && i < this->n)
{
return this->medicamente[i];
}
}
friend class RetetaCompensata;
virtual float getValoare()
{
float sum = 0;
for (int i = 0; i < this->n; i++)
{
sum=sum+this->medicamente[i].getPret();
}
return sum;
}
friend ifstream& operator>>(ifstream& consola, Reteta& x)
{
char aux[30];
float z;
consola >> x.n;
if (x.medicamente)
delete[] x.medicamente;
x.medicamente = new Medicament[x.n];
for (int i = 0; i < x.n; i++)
{
consola >> aux >> z;
Medicament m(aux, z);
x.medicamente[i] = m;
}
return consola;
}
};
class RetetaCompensata : public Reteta{
private:
float procentCompensat;
public:
RetetaCompensata(float procent)
{
this->procentCompensat = procent;
}
RetetaCompensata(Reteta r, float procent)
{
this->procentCompensat = procent;
this->n = r.n;
this->medicamente = new Medicament[r.n];
for (int i = 0; i < r.n; i++)
{
this->medicamente[i] = r.medicamente[i];
}
}
float getValoare()
{
float sum = 0;
sum = this->procentCompensat*this->getValoare();
return sum;
}
friend ostream& operator<<(ostream& consola, RetetaCompensata &x)
{
consola << "**Procent compensat: " << x.procentCompensat << endl;
consola << "Numar de medicamente: " << x.n << endl;
consola << " -->Lista Medicamente<-- " << endl;
for (int i = 0; i < x.n; i++)
{
consola << x.medicamente[i] << " ";
}
return consola;
}
};
void main()
{
//1
Medicament nurofen("Nurofen", 11.25f);
Medicament aspirina = nurofen;
aspirina.setDenumire("Aspirina");
aspirina.setPret(4.5f);
Medicament bixtonim("Bixtonim", 8.2f);
Medicament temp;
temp = nurofen;
cout << temp << endl;
cout << nurofen << endl;
cout << aspirina << endl;
//2
Medicament medicamente[] = { aspirina, nurofen };
Reteta r0(medicamente, 2);
cout << r0 << endl;
//3
Reteta r1;
r1.adaugaMedicament(nurofen);
r1.adaugaMedicament(aspirina);
for (int i = 0; i < r1.getN(); i++)
{
cout << r1[i] << endl;
}
//4
RetetaCompensata r2(0.5);
r2.adaugaMedicament(bixtonim);
r2.adaugaMedicament(aspirina);
RetetaCompensata r3(r1, 0.2);
cout << "AFISARE R3" << endl;
cout << r3 << endl << endl;
Reteta* p = &r1;
cout <<"Valoare reteta r1: "<< p->getValoare() << endl;
//5
Reteta r4;
ifstream fisier("retete.txt");
fisier >> r4;
cout << r4 << endl;
//6
cout << endl << "Afisare Lista :" << endl << endl << endl;
list<Reteta> R;
list<Reteta>::iterator it;
R.push_back(r0);
R.push_back(r1);
R.push_back(r3);
R.push_back(r2);
R.push_back(r4);
for (it = R.begin(); it != R.end(); it++)
{
cout << *it << " Valoare Reteta: " << it->getValoare() << endl << endl << endl; // error at this line when I compile
}
}
【问题讨论】：
-
Medicament operator=(Medicament x)赋值运算符应该返回一个引用，而不是一个新对象。为什么不使用std::string而不是char *？单独这样做会削减您编写的代码的主要部分。 -
我是新手。我必须这样做。几周后我将只玩 STL。
-
应该是相反的。现在使用 STL，稍后使用指针（很久以后）。
-
当您的类在构造函数中分配内存并在析构函数中释放内存时，您必须正确实现复制构造函数和复制赋值运算符。
-
嗯..您使用的是
std::list而不是std::string？说真的，如果您使用std::string而不是char *和std::vector<Medicament>而不是new Medicament[n]，那么所有这些代码都可以工作。
标签： c++ list stl destructor