constructor

[scsi]

Hi guys,

I am wondering about c++ default constructor.

Let's say I am trying to define a class, and letting default constructor to initialise it's value. The result of initialized variable is (using type int) -858993460> Why is it so?

[Thomas1965]

The clairvoyants are off duty now.
Can you show the code so that ordinary programmers can have a look?

[scsi]

I beg your pardon

#include <iostream>
using namespace std;

class darbuotojas
{
public:

	
	int get_amzius()
	{
		return amzius;
	}
	void set_amzius(int amzius);

	void give_amzius()
	{
		cout << "darbuotojo amzius - " << get_amzius() << endl;
	}

private:
	int amzius;
};

#include "darbuotojas.hpp"
using namespace std;



void darbuotojas::set_amzius(int naujas_amzius)
{
	amzius = naujas_amzius;
}

int main()
{
	darbuotojas ateina;
	ateina.give_amzius();
	ateina.set_amzius(20);
	ateina.give_amzius();
	ateina.set_amzius(25);
	ateina.give_amzius();

	return 0;
}

[Thomas1965]

At the moment nobody initializes the var amzius. The compiler will create a default constructor for you but it doesn't know anything about your vars.
The best is to create a constructor yourself like:

class darbuotojas
{
public:
  darbuotojas(int a) { amzius = a;}
  // and/or
  darbuotojas() { amzius = 0; // or any other value}

  // allyour code here
};

BTW. What does darbuotojas mean? What language is it?

[scsi]

Employee. It is Lithuanian

[cire]

Why is it so?

Because POD (plain old data) types are not initialized to any particular value unless you let the compiler know you want them to be.

#include <iostream>

struct Pod
{
    int value;
};


void avoid_uninitialized_error(Pod&) // To fake out VC++.
{
}

int main()
{
    {
        Pod p;  // uninitialized

        avoid_uninitialized_error(p);

        std::cout << p.value << '\n';
    }
   
    {
        Pod p = Pod();  // initialized

        std::cout << p.value << '\n';
    }

}

[scsi]

Thanks!