VC++ On run Error (Destructor)

[NoobImbaPro]

Compiler throws me the error at bottom of post, what I got wrong in my code?

#include <cstdlib>
#include <iostream>
#include <string>

#define MAX_CHAR_LENGTH 20

using namespace std;

class DIstudent
{
private:
	int *grades;
	float average;
	char *name;
	char *surname;
public:
    DIstudent(char *onoma, char *eponimo, int, int, int, int);
    DIstudent(const DIstudent &);
   ~DIstudent();
    DIstudent& operator=(const DIstudent& );
    void print() const;
};

DIstudent::DIstudent(char *onoma, char *eponimo, int bathmos1, int bathmos2, int bathmos3, int bathmos4)
{
    grades = new int(4);
    grades[0] = bathmos1;
    grades[1] = bathmos2;
    grades[2] = bathmos3;
    grades[3] = bathmos4;

	
    int av = 0;
    for(int i=0; i<4; i++)
        av+=grades[i];

    average = (float)av/4;
    
    int l;
    
    l = ( strlen(onoma) > MAX_CHAR_LENGTH ) ? MAX_CHAR_LENGTH : strlen(onoma);
    name = new char(l+1);
    strcpy(name, onoma);
    name[l] = 0;
    
    l = ( strlen(eponimo) > MAX_CHAR_LENGTH ) ? MAX_CHAR_LENGTH : strlen(eponimo);
    surname = new char(l+1);
    strcpy(surname, eponimo);
    surname[l] = 0;
    
    cout << name << " " << surname << " created\n";
}

DIstudent::DIstudent(const DIstudent &obj)
{
    grades = new int(4);
    for(int i=0; i<4; i++) { grades[i] = obj.grades[i]; }
    
    average = obj.average;
    
    name = new char(strlen(obj.name)+1);
    strcpy(name, obj.name);
    
    surname = new char(strlen(obj.surname)+1);
    strcpy(surname, obj.surname);
    
    cout << name << " " << surname << " copied\n";
}

DIstudent::~DIstudent()
{
    cout << name << " " << surname << " destroyed\n";
    
    delete[] grades;
    delete[] name;
    delete[] surname;
}

DIstudent& DIstudent::operator=(const DIstudent &obj)
{
    if (this == &obj)
        return *this;
    
    delete[] grades;
    delete[] name;
    delete[] surname;
    
    grades = new int(4);
    for(int i=0; i<4; i++) { grades[i] = obj.grades[i]; }
    
    average = obj.average;
    
    name = new char(strlen(obj.name)+1);
    strcpy(name, obj.name);
	
    surname = new char(strlen(obj.surname)+1);
    strcpy(surname, obj.surname);
    
    cout << name << " " << surname << " assinged\n";

    return *this;
}

void DIstudent::print() const
{
     cout << name << " " << surname << endl
     << "The grades are: ";
     for(int i=0; i<4;i++)
         cout << grades[i] << " ";
     cout << endl;
     cout << "The average is: " << average << endl;
}

int _tmain(int argc, _TCHAR* argv[])
{
    const DIstudent pupil_01("Stelios", "Kapsalis", 2, 4, 6, 8);
    DIstudent pupil_02 = pupil_01;
    DIstudent pupil_03("Giannhs", "Agiannhs", 8, 8, 9, 9);

    pupil_01.print();
    pupil_02.print();
    pupil_03.print();

    pupil_02 = pupil_03;

    pupil_02.print();
    
    system("pause");
    return 0;
}

Error:
Windows triggered a breakpoint...

This may be due to a corruption of the heap, which indicates a bug in project2.exe or any of the DLLs it has loaded.

This may also be due to the user pressing F12 while project2.exe has focus.

The output window may have more diagnostic information.

 

[s3rius]

You should REALLY start using std::string if at all possible.

Using manual memory allocation and strcpy like that is bound to stab you in the back.

In this case the segfault is caused by the destructor's

   delete[] xxx;

The actualy problem lies in your constructors / assignment operator:

grades = new int(4);

You're trying to allocate an int array of size 4, but you're only allocating a single int of value 4.

grades = new int[4];

This is declaring an int array.
Same problem with the char* arrays for name and surname.

That's why delete[] segfaults, bcause it tries to get the size of the array you've given it. Since it is no array it will only find garbage data and will probably start wiping significant parts of your application RAM. Segfault means that your program actually tried to delete memory that is used by other programs or maybe even by Windows.

With std::string you wouldn't run into any troubles. If you can't use std::string then I'd suggest making a small class that acts like a string and encapsulates all the strlen strcpy new delete stuff.

 

[NoobImbaPro]

oh thanks, i could use string but teacher wants char*
I don't really have to make class for that, maybe in a some more serious project.