Thread: A little class problem

This is a class I'm using for a game I'm making and it is giving me these error;

Code:

C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|18|error: ISO C++ forbids initialization of member `x'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|18|error: making `x' static|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|18|error: ISO C++ forbids in-class initialization of non-const static member `x'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|19|error: ISO C++ forbids initialization of member `y'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|19|error: making `y' static|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|19|error: ISO C++ forbids in-class initialization of non-const static member `y'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|21|error: ISO C++ forbids initialization of member `right'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|21|error: making `right' static|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|21|error: ISO C++ forbids in-class initialization of non-const static member `right'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|22|error: ISO C++ forbids initialization of member `left'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|22|error: making `left' static|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|22|error: ISO C++ forbids in-class initialization of non-const static member `left'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|23|error: ISO C++ forbids initialization of member `up'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|23|error: making `up' static|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|23|error: ISO C++ forbids in-class initialization of non-const static member `up'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|24|error: ISO C++ forbids initialization of member `down'|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|24|error: making `down' static|
C:\Users\Bijan\Documents\C++ Programs\My SDL project\main.cpp|24|error: ISO C++ forbids in-class initialization of non-const static member `down'|
||=== Build finished: 18 errors, 2 warnings ===|

here is the class

Code:

class character{
    public:
    void handle_events();

    int x = 0;
    int y = 0;

    int right = 0;
    int left = 0;
    int up = 0;
    int down = 0;

    private:
    int collision_x();
    int collision_y();
};

The errors mean just what they say. You cannot give member objects a value in a class definition, since quite frankly they don't exist. They do not exist until an object of that class is constructed, and so this initialization is the job of the constructor.

Originally Posted by MK27

Those values will all be initialized to 0 by default anyway (when an actual object is instantiated).

This is of course not true.

Code:

#include <iostream>
class test {
    public:
        int x;
};

int main() {
    test foo;
    std::cout << foo.x << std::endl;
    return 0;
}

Code:

$ ./a.out
3616756

Thanks you guys.

Originally Posted by MK27

Um:

Code:

using namespace std;

class test {
	public:
		int x, y;
		test() {}
};

int main() {
	test eg;

	cout << eg.x << eg.y;

	return 0;
}

00

Maybe a constructor is required or it is just g++, but I'm sure I've read the standard ensures this too. Lemme go consult BS...

And what did you think I was using?

Code:

andrewf@ubuntu:~$ cat >mk.cpp
#include <iostream>
using namespace std;

class test {
    public:
        int x, y;
        test() {}
};

int main() {
    test eg;
    
    cout << eg.x << eg.y;

    return 0;
}
andrewf@ubuntu:~$ g++ mk.cpp
andrewf@ubuntu:~$ ./a.out
134514368-1080144264

Originally Posted by MK27

I wasn't using any switches, gcc 4.3.2.

I guess the point is that I shouldn't count on that (time to go thru some code! ARGGGHH!). I could have sworn I read this was a standard thing somewhere.

It's supposed to default-construct each member of the class. But default-construct for int doesn't do a great deal.