Thread: operator int()

the book im reading has an exercise to make a class Int and overload the basic operators. there is 2 things i dont understand. it asks for bounds checking, but i dont know why the answer in the back of the book needs to convert it to long double. the other thing i dont get is 'operator int()'. when does this come in play in the class? its a conversion from Int to type int, i know that much. but when is this operator called. thanks in advance for responses

Code:

//////////////////////////class Int/////////////////////////
class Int
{
private:
	int i;
public:
	Int(): i(0)  //set default value (constructor)
	{	}

	Int(int integer):	i(integer)	  //1-arg constructor
	{	}
	
	void put_int()			//display int
	{ cout << i << endl; }

	void get_int()	//get int
	{ cin >> i; }

	operator int()   //conversion operator from Int to int
	{	return i;	}

	Int operator + (Int i2)
	{	return limit_check(long double(i) + long double(i2));	}

	Int operator - (Int i2)
	{	return limit_check(long double(i) - long double(i2));	}

	Int operator * (Int i2)
	{	return limit_check(long double(i) * long double(i2));	}

	Int operator / (Int i2)
	{	return limit_check(long double(i) / long double(i2));	}

	Int limit_check(long double num)
	{
		if(num > 2147482648.0L || num < -2147482648.0L)
		{
			cout << "\nOverflow error:  Exiting." << endl;
			exit(1);
		}

		return Int(int(num));
	}

};

/////////////////////////////////////////////////////////////

when is this operator called

It is called when a variable of type int is expected. For example:

Code:

void func(int nParam)
{
}

int main()
{
    Int a=5;

    func(a);
}

In this case 'a' will call operator int() to resolve itself to type 'int'. Quite ingenious really.

>>Int a=5;
int a=5;

Geez.

Maybe you misunderstand, XSquared. Int is a class.

Whoops. You're right. Name your clases differently, geez!

Name your clases differently, geez!

I agree. I would have called it CInt.

why is it required to convert it to long double and check the bounds?

I don't know, it does seem a bit pointless doesn't it.