Thread: program variables

Hello..

Im working on a class that would store different variables for my application..

Code:

class datalist {
public:
	datalist() {}

	char *name;
	unsigned short type;
	void *p;
	datalist *next;
};

It would be possible to store char * (string), char ** (string list), and integer.
type 0 = integer, 1 = string, 2-> = string list (the number of strings)

p is the pointer to data.

Is it smart doing things like that?

I want a function that would return string (if char*) or first string (if char**)

Code:

int readdata(datalist *read) {
	char *value = 0;
	if (read && read->type) {
		if (read->type > 1) 
			value = (char **)(read)->p; // <- problem
		else
			value = (char *)(read)->p;

		printf("value: %s\n", value);
	}
	return 0;
}

The code is not okay, I get error if I cast (char**)(read)->p[0] - "'void *' : unknown size".. Im not sure how should I do it? Is it smart doing things that way?

> Is it smart doing things like that?
I would suggest you look up how to do templates, which allow you to create instances of your class suited to whatever data type(s) you're interested in storing.

Also you do't need to store an abstract representation of types. You can use typeid().

Code:

int x = 0;
double y = 0;
int* ptr = &x;
int z = 0;

if( typeid(int) == typeid(x) ) std::cout << "Match!\n"; else std::cout << "No Match!\n";
if( typeid(int) == typeid(y) ) std::cout << "Match!\n"; else std::cout << "No Match!\n";
if( typeid(int*) == typeid(ptr) ) std::cout << "Match!\n"; else std::cout << "No Match!\n";

//or by comparing objects directly...

if( typeid(x) == typeid(z) ) std::cout << "Match!\n"; else std::cout << "No Match!\n";