错误：“函数”不是非静态数据成员或“类”的基类

Question

I'm trying to understand the syntax of C++ since I'm almost fresh to the language, but I dont know what error exactly I'm facing..

I have the Component class implemented on my code and works fine

namespace GUI
{
class Component : public sf::Drawable
                , public sf::Transformable
                , private sf::NonCopyable
{
    public:
            //Variables
};
}

and also the book Im studying asks me to implement another class called Container in the GUI namespace

Container::Container()
: mChildren()
, mSelectedChild(-1)
{
}
void Container::pack(Component::Ptr component)
{
    mChildren.push_back(component);
    if (!hasSelection() && component->isSelectable())
        select(mChildren.size() - 1);
}
bool Container::isSelectable() const
{
    return false;
}

What I don't get is the way he is implementing the class, which is giving me the syntax error in the title of the post.. "Error: "mChildren" is not a Non static data member or base class of class "GUI::Container"" .

I tryed the futher code:

class Container:

{

Container::Container()
: mChildren()
, mSelectedChild(-1)
{
}
void Container::pack(Component::Ptr component)
{
    mChildren.push_back(component);
    if (!hasSelection() && component->isSelectable())
        select(mChildren.size() - 1);
}
bool Container::isSelectable() const
{
    return false;
}
};

But I'm still getting syntax error =/ what exactly is going wrong and what shoul I read regarding this subject? (I also read C++ guidelines books but I didnt find the answer there cos I probably dont know how to refer to this problem) thanks in advance

Answer 1

When you define your methods inside your class declaration, you can't use the :: scope resolution operator .

Also your methods should probably in public. And finally you have to be sure that your mChildren member is correctly define.

class Container
{
    // ...

public:
    Container()
//  ^^
       : mChildren()
       , mSelectedChild(-1)
    {
    }
    void pack(Component::Ptr component)
//       ^^
    {
         // ...
    }
    bool isSelectable() const
//       ^^
    {
        // ...
    }

private:
    std::vector<Component::Ptr> mChildren;   // Example of a definition of mChildren
    //          ^^^^^^^^^^^^^^ replace with the good type

};

Answer 2

From this code you are using mChildren, but it is not defined in your Container class. What is mChildren supposed to be?

If it is a vector of Component::Ptr you need to define it in your class.

std::vector<Component::Ptr>mChildren;

Answer 3

Why are you initializing mChildren in the constructor initialization list? More specifically what is this call mChildren() doing? Try removing that call and see what happens.