Thread: istream overload

Here I am doing more stuff with my "any" type.

I'm overloading the istream operator right now... I can't figure out why it isn't working right.

As far as the function itself, that works. Locally, the commented out any_cast line returns the correct value.

But it isn't acting like it actually changed the passed "operand"... because it doesn't do a thing if you try to use any_cast outside of the overload.

Any ideas as to what is wrong? Thanks!

Code:

	istream& operator >>(istream & is, any & operand)
	//precondition:  input stream is open for reading
	//postcondition: the next string from input stream is has been read
	//               and stored in str
	{
		char temp[81] = "";	// not longer than screen length
		char ch = 0;
		int i = 0;
    
		while (i <= 80 && is.get(ch) && ch != '\n')
		{
			temp[i++] = ch;
		}
		temp[i] = '\0';

		operand = temp;

		//cout << any_cast<char*>(operand) << endl;
    
		return is;
	}

And if it does work, I get giberish characters.

if I add a line like this:

operand = 'a';

then it works fine... it gives me an a later. But if I give it the value of temp... it doesn't

Its also useless to always assign it a value.

I was specifically trying not to use a string.

I understand what you're saying (I've had that problem before)... but where was I using pointers?

and btw, I'm not actually using boost, its just something from boost... so I don't have lexical cast.

Originally posted by grib
I also see no point to having an any that takes on only one value.

It won't always take a string, trust me... I just want to get it working with strings first.

that was actually a temporary solution. I know what you mean though.

any isn't a union... it is a variant.

It works exactly like I want it to... except it goes out of scope.

static would work, only the variable is always the same, so if you call it again, the other value changes.

Here's my latest code:

Code:

	istream& operator >>(istream & is, any & operand)
	//precondition:  input stream is open for reading
	//postcondition: the next string from input stream is has been read
	//               and stored in operand
	{
		static char temp[81];	// not longer than screen length
		char ch;
		int i = 0;
    
		while (i <= 80 && is.get(ch) && ch != '\n')
			temp[i++] = ch;

		temp[i] = '\0';

		//cout << any_cast<char*>(operand) << endl;

		if (isint(temp))			// if it is an integer, convert it to one
			operand = atoi(temp);
		else if (isfloat(temp))		// if it is a float or double, convert it to one
			operand = atof(temp);
		else						// otherwise, just store a string
			operand = temp;
   
		return is;
	}