Original Post
This would go in the beginner forum, but it appears to be down. And I'm not really a beginner anymore, but these are beginner problems that, for some rediculous reason, refuse to let me solve them. So here's the two issues: 1) Default constructors. You need them if you're not passing a class (or struct, in my case), any values during instantiation. I'm creating an instance of the struct (called Position) once, giving it the values I specified. Position is immediately getting passed into another function (the constructor for Button) by value. I get compiler errors, telling me I need a default constructor. Great. I give it default values to make it happy. So it finally compiles, runs... hits the Position constructor twice. The first is from the initial creation, which works fine. The second is in the Button constructor, on the function arguments line. I wasn't aware passing by value would call the constructor again. Copy constructor, yes (although I don't need a copy constructor since the struct is doing nothing with dynamic memory). Default constructor though? Well, it's hosing everything up, because that's what is being passed into the function. 2) Function pointers. I'm a bit rusty on this, so I looked it up. I got everything to compile... all looked good. I'm grabbing the address of a function (called Menu::CreateHostMenu) and passing it into another function (the constructor for Button). But upon running my program, I get this error: Am I missing something silly like usual? [Edited by - marshdabeachy on January 26, 2007 5:05:08 AM]
Quote:I checked the constructor Button, and about half the time it's being set properly, and the other half of the time it's being set to NULL. At all times it errors. Obviously something's screwy, but I can't figure out what. The problems are both in the same code. Here it is:
Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.
// button header
class Menu;
typedef void (Menu::*MenuFunct)(void);
struct Position {
Position(unsigned x=0, unsigned y=0) : _x(x), _y(y) {}
unsigned _x, _y;
};
struct Area {
Area(unsigned w=0, unsigned h=0) : _w(w), _h(h) {}
unsigned _w, _h;
};
class Button {
public:
Button(std::string text, MenuFunct funct, Position pos, Area area);
private:
std::string _text;
MenuFunct _funct;
Position _pos;
Area _area;
};
// button implementation
Button::Button(std::string text, MenuFunct funct, Position pos, Area area) {
this->_text = text;
this->_funct = funct;
this->_pos = pos;
this->_area = area;
}
// menu implementation
void Menu::CreateMainMenu() {
buttons.push_back( new Button( "Host Game", &Menu::CreateHostMenu, Position(100, 100), Area(100, 20) ) );
}
