C / C++ / MFC

Iain Clarke wrote:

2/ Less trivially, the first example just calls the constructor. The second example makes two objects, (obj, and a temp one), then copies temp to obj, then destroys the temp object.

#include <iostream>
using namespace std;

class MyClass
{
public:
	int _a, _b;
	MyClass(){}
	MyClass(int a, int b):_a(a), _b(b){}
	// copy constructor and assignment operator arbitrarly messed up.
	MyClass(const MyClass & proto)
	{
		_a = 0;
		_b = 0;
	} 
	MyClass & operator = (const MyClass & proto)
	{
		_a = proto._b;
		_b = proto._a;
		return *this;
	}
};


void main()
{
	MyClass my1(3,2);
	MyClass my2=MyClass(3,2);

	MyClass my3(my1);
	MyClass my4;
	my4=my1;

	cout << "my1: " << my1._a << " " << my1._b << endl;
	cout << "my2: " << my2._a << " " << my2._b << endl;
	cout << "my3: " << my3._a << " " << my3._b << endl;
	cout << "my4: " << my4._a << " " << my4._b << endl;

}
</iostream>

my1: 3 2
my2: 3 2
my3: 0 0
my4: 2 3

CMyCLass my1 = my2;

CMyClass my1(my2);

MyClass my2 = MyClass(3,2);

MyClass my2(3,2);

CPallini wrote:

What do you think?

class MyClass
{
public:
	int _a, _b;
	MyClass()
	{
		TRACE0("Blank Constructor\n");
	}
	~MyClass()
	{
		TRACE0("Destructor\n");
	}
	MyClass(int a, int b):_a(a), _b(b)
	{
		TRACE2("Parameter Constructor(%i,%i)\n", a,b);
	}
	// copy constructor and assignment operator arbitrarly messed up.
	MyClass(const MyClass & proto)
	{
		_a = 0;
		_b = 0;
		TRACE0("Copy Constructor\n");
	} 
	MyClass & operator = (const MyClass & proto)
	{
		_a = proto._b;
		_b = proto._a;
		TRACE0("Copying\n");
		return *this;
	}
};

void main()
{
	MyClass my1(3,2);
	MyClass my2=MyClass(30,20);
}

Parameter Constructor(3,2)
Parameter Constructor(30,20)

FILE *p = fopen ("foo", "rw");

HANDLE FileToHandle (FILE *f)
{
    return (HANDLE)(f->_file);
}

<br />
HANDLE FileToHandle (FILE *f)<br />
{<br />
    return (HANDLE)(_get_osfhandle(f->_file));<br />
}<br />

Hamid. wrote:

No you want to close your program and open it again