Non static members in C++ - c++

Question

error C2648: 'stack::Y' : use of member as default parameter
requires static member
error C2648: 'stack::X' : use of member as default parameter
requires static member
IntelliSense: a nonstatic member reference must be relative to a
specific object
IntelliSense: a nonstatic member reference must be relative to a
specific object
Please, help to fix it
class stack{
node *head, *tail;
int maze[10][10], X, Y, _X, _Y;
public:
stack():head(0), tail(0){};
~stack();
void load();
void makelist(int = X, int = Y); //error is here
void push(int, int);
void pop();
void print();
};
void stack::load(){
ifstream fin("maze.txt");
fin >> X >> Y >> _X >> _Y;
cout << "Loaded matrix:" << endl << endl;
for (int i = 0; i < 10; i++){
for (int j = 0; j < 10; j++){
fin >> maze[i][j];
if (i == X && j == Y)
cout << "S ";
else if (i == _X && j == _Y)
cout << "F ";
else
cout << maze[i][j] << " ";
}
cout << endl;
}
}
void stack::makelist(int x, int y)
{
if (x == _X && y == _Y)
{
push(x, y);
print();
pop();
return;
}
if (x > 0) if (maze[x - 1][y] == 0) { maze[x][y] = 1; push(x, y); makelist(x - 1, y); pop(); maze[x][y] = 0; }
if (x < 9) if (maze[x + 1][y] == 0) { maze[x][y] = 1; push(x, y); makelist(x + 1, y); pop(); maze[x][y] = 0; }
if (y > 0) if (maze[x][y - 1] == 0) { maze[x][y] = 1; push(x, y); makelist(x, y - 1); pop(); maze[x][y] = 0; }
if (y < 9) if (maze[x][y + 1] == 0) { maze[x][y] = 1; push(x, y); makelist(x, y + 1); pop(); maze[x][y] = 0; }
}
<...>
int main()
{
stack obj;
obj.load();
obj.makelist();
system("pause");
return 0;
}

Answer 1

(this is a correction to my old answer, which was incorrect)
It seems that you want to use a non-static member as a default value for a parameter, and the compiler tells you this is impossible. You can use an overload as a workaround:
class stack{
node *head, *tail;
int maze[10][10], X, Y, _X, _Y;
public:
void makelist() {makelist(X, Y);} // I added this overload to do what you want
void makelist(int x, int x);
...
};
Some people would say overloading is better than using default values, because you probably don't want to support calling makelist with 1 parameter, only with 0 or 2 parameters (or, if you actually want this, you can add another overload, with 1 parameter).

Answer 2

You have a spurious "=" character in your code; replace your line with error with the following:
void makelist(int X, int Y);
The "=" character makes it look like the declaration has default parameters whose values are X and Y, which is totally not what you intended to do.
In addition, it is customary to have the same parameter names in declaration and definition:
void makelist(int x, int x); // declaration - I replaced X by x, Y by y
...
void stack::makelist(int x, int y) // definition - has lowercase names, which are good
{
...
}

Answer 3

Get rid of those = signs in the function declaration:
void makelist(int x, int y);
so it's just like the definition:
void stack::makelist(int x, int y)
{

Answer 4

Presuming you meant to use default values
void makelist(int x_ = X, int y_ = Y); //error is here
This is not allowed as the default values must be compiletime constants or compiletime addressable, which members of a not instantiated class are not.
The compiler needs an address be able to generate the code.
You can overload the function
void makelist(int x_, int y_);
void makelist() { makelist(X,Y); }
And so get nearly the same behaviour as you asked.
If you have a problem with _X & _Y then its because the compiler reserves _??? for itself or libraries.