Виртуальные базовые классы и деструкторы
05.09.2018, 00:36. Показов 2156. Ответов 4
Пожалуйста, помогите разобраться. Решаю задачу 6 глава 17 из Праты. Кратко: в определении виртуального абстрактного класса определяю деструктор: | C++ | 1
| virtual ~abstr_emp() = 0 {}; |
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В процессе освобождения памяти, выделенной динамически в массиве указателей, по цепочке вызываются деструкторы по умолчанию вплоть до этого | C++ | 1
| virtual ~abstr_emp() = 0 {}; |
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(В функции: | C++ | 1
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| void free(abstr_emp** pc, int nn)
{
for (int i = 0; i < nn; i++)
{
delete pc[i];
};
} |
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И здесь выскакивает исключение:
Exception thrown: read access violation.
_Pnext was 0x38E9DC.
Указывает на (если это поможет):
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| // MEMBER FUNCTIONS FOR _Container_base12
inline void _Container_base12::_Orphan_all()
{ // orphan all iterators
#if _ITERATOR_DEBUG_LEVEL == 2
if (_Myproxy != 0)
{ // proxy allocated, drain it
_Lockit _Lock(_LOCK_DEBUG);
for (_Iterator_base12 **_Pnext = &_Myproxy->_Myfirstiter;
*_Pnext != 0; *_Pnext = (*_Pnext)->_Mynextiter) // - ошибка!
(*_Pnext)->_Myproxy = 0;
_Myproxy->_Myfirstiter = 0;
}
#endif /* _ITERATOR_DEBUG_LEVEL == 2 */
} |
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Причем ошибка возникает с данными, кот были считаны из бинарников. При первом запуске и записи в бинарник освобождение памяти идет на ура.
Полный код программы:
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| #pragma once
#ifndef EMP_H
#define EMP_H
#include <iostream>
#include <fstream>
#include <string>
using std::string;
using std::ofstream;
using std::ostream;
using std::ifstream;
enum classType { Employee, Manager, Fink, Highfink };
class abstr_emp
{
private:
string fname;
string lname;
string job;
public:
abstr_emp() : fname("Noname"), lname("No_last_name"), job("No_job") {};
abstr_emp(const string & fn, const string & ln, const string & j) :
fname(fn), lname(ln), job(j) {}
virtual void ShowAll() const;
virtual void SetAll();
friend ostream& operator<<(ostream &os, const abstr_emp & e);
virtual ~abstr_emp() = 0 {};
virtual bool writeall(ofstream & fout) const;
virtual bool getall(ifstream &fin);
};
class employee: public abstr_emp
{
public:
employee() :abstr_emp() {};
employee(const string& fn, const string & ln, const string &j) :
abstr_emp(fn, ln, j) {};
virtual void ShowAll() const { abstr_emp::ShowAll(); };
virtual void SetAll() { abstr_emp::SetAll(); };
virtual bool writeall(ofstream &fout) const;
virtual bool getall(ifstream &fin) { return abstr_emp::getall(fin); };
};
class manager : virtual public abstr_emp
{
private:
int inchargeof;
protected:
int InChargeOf() const { return inchargeof; };
int & InChargeOf() { return inchargeof; };
public:
manager() :abstr_emp(), inchargeof(0) {};
manager(const string & fn, const string & ln, const string & j, int ico = 0) :
abstr_emp(fn, ln, j), inchargeof(ico) {};
manager(const abstr_emp& e, int ico) : abstr_emp(e), inchargeof(ico) {};
manager(const manager &m) : abstr_emp(m), inchargeof(m.inchargeof) {};
virtual void ShowAll() const;
virtual void SetAll();
virtual bool writeall(ofstream &fout) const;
virtual bool getall(ifstream &fin);
};
class fink : virtual public abstr_emp
{
private:
string reportsto;
protected:
const string ReportsTo() const { return reportsto; };
string & ReportsTo() { return reportsto; };
public:
fink() :abstr_emp(), reportsto("No_reprs") {};
fink(const string & fn, const string & ln, const string & j, const string & rpo) :
abstr_emp(fn, ln, j), reportsto(rpo) {};
fink(const abstr_emp & e, const string& rpo) : abstr_emp(e), reportsto(rpo) {};
fink(const fink & e) : abstr_emp(e), reportsto(e.reportsto) {};
virtual void ShowAll() const;
virtual void SetAll();
virtual bool writeall(ofstream &fout) const;
virtual bool getall(ifstream &fin);
};
class highfink : public manager, public fink
{
public:
highfink() : manager(), fink() {};
highfink(const string & fn, const string & ln, const string & j, const string & rpo) :
manager(fn, ln, j), fink(fn, ln, j, rpo) {};
highfink(const abstr_emp &e, const string & rpo, int ico) :
manager(e, ico), fink(e, rpo) {};
highfink(const fink& f, int ico) :
manager(f, ico), fink(f) {};
highfink(const manager & m, const string & rpo) :
manager(m), fink(m, rpo) {};
highfink(const highfink & h) : manager(h), fink(h) {};
virtual void ShowAll() const;
virtual void SetAll();
virtual bool writeall(ofstream &fout) const;
virtual bool getall(ifstream &fin);
}; |
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| #include "Employee.h"
#include <memory>
using std::cerr;
using std::ios_base;
using std::fstream;
using std::cout;
using std::endl;
using std::cin;
const int MAX = 2;
abstr_emp *pc[MAX];
void usr_inp(abstr_emp** pc, int nn);
void show_it(abstr_emp** pc, int nn);
void free(abstr_emp** pc, int nn);
bool save2file(abstr_emp** pc, int nn, ofstream& fout);
bool read_from_file(abstr_emp** pc, int nn, ifstream& fin);
int main()
{
ofstream fout;
fout.open("f1.txt", ios_base::out | ios_base::app | ios_base::binary);
if (!fout.is_open())
{
cerr << "Error opening " << "f1.txt" << " file!\n";
exit(EXIT_FAILURE);
}
fout.seekp(0, fout.end);
long length = fout.tellp();
if (length == 0)
{
usr_inp(pc, MAX);
cout << "\n\nUr input to be written in a file: ";
show_it(pc, MAX);
if (save2file(pc, MAX, fout))
{
cout << "Saved successfully...";
}
fout.close();
}
else {
fout.seekp(0, fout.beg);
ifstream fin;
fin.open("f1.txt", ios_base::in | ios_base::binary);
if (!fin.is_open())
{
cerr << "Error opening " << "f1.txt" << " file!\n";
exit(EXIT_FAILURE);
}
if (read_from_file(pc, MAX, fin))
show_it(pc, MAX);
fin.clear();
fin.close();
cout << "Modify info? (Y/N): ";
char yn;
while (cin >> yn && tolower(yn) != 'n')
{
if (tolower(yn) == 'y')
{
free(pc, MAX);
usr_inp(pc, MAX);
if (save2file(pc, MAX, fout))
{
cout << "Saved successfully...";
break;
}
}
else {
cout << "Wrong value. Try again pls: ";
continue;
}
}
cin.get();
};
fout.close();
cout << "Programm terminating...\n";
free(pc, MAX);
cin.get();
return 0;
}
void usr_inp(abstr_emp** pc, int nn)
{
int W_class;
for (int i = 0; i < nn; i++)
{
cout << "Type of the worker (0 for Employee, 1 for Manager, 2 for Fink, 3 for HighFink):\n";
cin >> W_class;
cin.get();
switch (W_class){
case Employee: pc[i] = new employee;
break;
case Manager: pc[i] = new manager;
break;
case Fink: pc[i] = new fink;
break;
case Highfink: pc[i] = new highfink;
break;
default: cout << "Ur value has not been matched..\n";
break;
};
pc[i]->SetAll();
};
}
void show_it(abstr_emp** pc, int nn)
{
for (int i = 0; i < nn; i++)
pc[i]->ShowAll();
}
void free(abstr_emp** pc, int nn)
{
for (int i = 0; i < nn; i++)
{
delete pc[i];
};
}
bool save2file(abstr_emp** pc, int nn, ofstream& fout)
{
int i;
cout << "Saving to the file..\n";
for (i = 0; i < MAX; i++)
{
pc[i]->writeall(fout);
}
if (!fout)
{
cerr << "Smth went wrong while writing into the file..\n";
system("pause");
return false;
}
else return true;
}
bool read_from_file(abstr_emp** pc, int nn, ifstream& fin)
{
cout << "Reading the info from a file:\n";
int type;
int i = 0;
while (!fin.eof() && i < MAX)
{
fin.read((char *)&type, sizeof(type));
switch (type) {
case Employee: pc[i] = new employee;
break;
case Manager: pc[i] = new manager;
break;
case Fink: pc[i] = new fink;
break;
case Highfink: pc[i] = new highfink;
break;
default: cout << "ID Value has not been matched..\n";
system("pause");
break;
}
pc[i++]->getall(fin);
}
if (fin)
return true;
else return false;
} |
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| #include "Employee.h"
using std::cout;
using std::endl;
using std::cin;
void abstr_emp::ShowAll() const
{
cout << "Employee info:\n";
cout << "Name: " << fname << endl
<<"Last name: " << lname << endl
<<"Job: " << job << endl;
}
void abstr_emp::SetAll()
{
cout << "Input the name: ";
getline(cin, fname);
cout << "Lname: ";
getline(cin, lname);
cout << "Job: ";
getline(cin, job);
}
bool abstr_emp::writeall(ofstream & fout) const
{
fout.write((char*) &fname, sizeof(fname));
fout.write((char*) &lname, sizeof(lname));
fout.write((char*) &job, sizeof(job));
if (fout)
return true;
else return false;
}
bool abstr_emp::getall(ifstream & fin)
{
fin.read((char*)&fname, sizeof(fname));
fin.read((char*)&lname, sizeof(lname));
fin.read((char*)&job, sizeof(job));
if (fin)
return true;
else return false;
}
ostream & operator<<(ostream & os, const abstr_emp & e)
{
os << "Fname: " << e.fname << endl;
os << "Lname: " << e.lname << endl;
os << "Job: " << e.job << endl;
return os;
}
void manager::ShowAll() const
{
abstr_emp::ShowAll();
cout << "Inchargeof: " << InChargeOf() << endl;
}
void manager::SetAll()
{
abstr_emp::SetAll();
cout << "Inchargeof: ";
cin >> InChargeOf();
}
bool manager::writeall(ofstream & fout) const
{
classType Type = Manager;
fout.write((char*)&Type, sizeof(Type));
abstr_emp::writeall(fout);
fout.write((char*) &inchargeof, sizeof(inchargeof));
if (fout)
return true;
else return false;
}
bool manager::getall(ifstream & fin)
{
abstr_emp::getall(fin);
fin.read((char *) &inchargeof, sizeof(inchargeof));
if (fin)
return true;
else return false;
}
void fink::ShowAll() const
{
abstr_emp::ShowAll();
cout << "Reports to: " << ReportsTo() << endl;
}
void fink::SetAll()
{
abstr_emp::SetAll();
cout << "Reports to: ";
cin >> ReportsTo();
}
bool fink::writeall(ofstream & fout) const
{
classType Type = Fink;
fout.write((char*)&Type, sizeof(Type));
abstr_emp::writeall(fout);
fout.write((char*)&reportsto, sizeof(reportsto));
if (fout)
return true;
else return false;
}
bool fink::getall(ifstream & fin)
{
abstr_emp::getall(fin);
fin.read((char *)&reportsto, sizeof(reportsto));
if (fin)
return true;
else return false;
}
void highfink::ShowAll() const
{
cout << "Showing highfink output items: \n";
abstr_emp::ShowAll();
cout << "Inchargeof: " << manager::InChargeOf() << endl;
cout << "Reports to: " << fink::ReportsTo() << endl;
}
void highfink::SetAll()
{
abstr_emp::SetAll();
cout << "Inchargeof: ";
cin >> manager::InChargeOf();
cout << "Reports to: ";
cin >> fink::ReportsTo();
}
bool highfink::writeall(ofstream & fout) const
{
classType Type = Highfink;
fout.write((char*)&Type, sizeof(Type));
abstr_emp::writeall(fout);
const int ico = InChargeOf();
const string rpt = ReportsTo();
fout.write((char*)&ico, sizeof(ico));
fout.write((char*)&rpt, sizeof(rpt));
if (fout)
return true;
else return false;
}
bool highfink::getall(ifstream & fin)
{
abstr_emp::getall(fin);
int ico = manager::InChargeOf();
string rpt = fink::ReportsTo();
fin.read((char *)&ico, sizeof(ico));
fin.read((char *)&rpt, sizeof(rpt));
if (fin)
return true;
else return false;
}
bool employee::writeall(ofstream & fout) const
{
classType Type = Employee;
fout.write((char*)&Type, sizeof(Type));
return abstr_emp::writeall(fout);
} |
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Буду признателен за любую помощь!
0
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(
Сообщение от AntonyV
Сообщение было отмечено AntonyV как решение
