Question

Hey i’m trying to figure out Function pointers and how to pass them around/ declare them, but i’m having a little trouble passing a pointer in my Button class constructor and setting it’s member function pointer too the passed pointer.

• when i write Button(Func1) Button1 it says expected a ‘;’
• when i write Button(Func1); it says no default constructor for Button
• when i write Button(&Func1); it says Func1 requires an initializer
• when i write Button(&Func1()) Button1; it says expression must be lvalue or function designator

What am i doing wrong?

void Func1(){std::cout << "This is a function\n";};
void Func2(){std::cout << "This is another function\n";};

class Button
{
private:
    void (*Func)(void);

public:
    void Activate(){ Func() ;};

    Button( void (*Function)(void)){
        this->Func = Function;};
};

Button(&Func1) Button1;
Button(&Func2) Button2;

Button1.Activate();
Button2.Activate();

Answer 1

This code has wrong syntax:

Button(&Func1) Button1;
Button(&Func2) Button2;

It should be:

Button Button1(&Func1);
Button Button2(&Func2);

And function pointer declaration:

void (*Func)(void);

Leave without void in parameters:

void (*Func)();

Edit: Working example at ideone.