Thread: Help in writing a class to file and calling a constructor

Hello!

I got one class named Hired and want to write the whole class into a file. But upon execution the program stops and ends without even create the file.
Also; how do I call the construtor that takes the INT paramter?.... Ex: Hired(int i = 1); does not seem to work, it still calls the Hired() that takes no parameters?!

The CLASS

Code:

class Hired
{
private:
    int      nr;                       
    int      ant_barn;                 
public:
    Hired (int n)
    {
        cout << "Hired nr: (100-999)" << endl;
        cin >> nr;
        cout << "Ant barn: 0-20" << endl;
        cin >> ant_barn;
    }

    Hired ()
    {
        cout << "\n\nWARNING 1: SHALL NOT RUN THIS CONSTRUCTOR\n\n";
    }
    void write_file(ofstream* out)
    {
        *out << nr;
        *out << ant_barn << endl;
    }
  
    void display()
    {
        cout << "Nr: " << nr;
        cout << "ant barn: " << ant_barn;
        cout << endl << endl;
    }

GLOBALS

Code:

//Globals
Hired* hired[100];     
int lastused = 0;

The main program.

Code:

int main()
{
//Filling in at least one "hired" with data:
    hired[lastused].Hired(lastused); //How do I call the Constructor that takes INT as a parameter in my class? SInce this line does not work!!
 I've also tried switching the "." with ->, did not work
    lastused = lastused + 1;

//To file
    ofstream myfile("hired.dta", ios::out | ios::ate);
    for (i = 1; i < lastused; i++)
    {
        hired[i]->write_file(&myfile); //Failure here or/and line below... I've also tried "hired[i].write_file(&myfile);
        hired[i]->display();
    }
    myfile.close();


    //To memory
    Hired* a;
    ifstream myfile2("hired.dta", ios::in);
    if (myfile2)                            //Read data in to file
    {
        i = 0;
        myfile2.read((char*) &a, sizeof(Hired));
        while (!myfile2.eof() &&  lastused >= i)
        {
            myfile2.read((char*) &a, sizeof(Hired));
            hired[i] = a;
            ++i;
            hired[i]->display();
        }
    }
    cout << "DONE";
    return 0;
}

Marked the lines that I am stumbled at with red color.

How do I call the constructor in my class, when my "hired" is a pointer with array of type Hired.

PS: If I made the "hired" pointer array variable of no pointer type, this works, then I just switch "->" with ".". But I want to work with pointers now!
PS2: CodeBlocks editor, compiler GCC

1.) You're trying to access a pointer that points to garbage.

hired[lastused] = new Hired(int);

2.) Don't try to call a constructor explicitally, it's called upon "construction." To call the constructor
with arguments, initialize the class using that constructor:

hired[lastused] = new Hired(50);

3.) I'd move thouse couts and cins into your main loop.

{
std::cout << "Hired nr: ";
std::cin >> nr;
std::cout << "Ant barn: ";
std::cin >> ant_barn;

hired[lastused] = new Hired(nr, ant_barn);
lastused++;
hired[lastused]->DoStuff();
}

4.) When working with a pointer, use -> instead of .

Hired h(50);
h.write_file;

OR

Hired* h = new Hired(50);
h->write_file;
delete h;


If you use new, you need to use delete somewhere.

Works now! Lovely, love you! Knew it was simple, just...