Multiple public/private keyword in class definition

Question

I have seen multiple public and private keywords in a class definition, like the example below:

class myClass
{
  public:
    void func1(){}
  public:
    void func2(){}
  private:
    int x;
    int y;
  private:
    int z;
    int baz;
};

What is the practical use of this (if any)? Is there any situation in which this could be useful?

Answer 1

Is there any situation in which this could be useful?

I can think of a situation where it would be very problematic otherwise:

 class myClass
{
  public:
    void func1(){}
  public:
    void func2(){}
  COORDINATES;    // <-- Note the macro here!
  private:
    int z;
    int baz;
};

which, after the expansion of the COORDINATES macro, becomes:

class myClass
{
  public:
    void func1(){}
  public:
    void func2(){}
  private:
    int x;
    int y;
  private:
    int z;
    int baz;
};

If multiple private / public keywords weren't allowed, it would be very painful to do it. Although using macros isn't good practice; neither is introducing access modifiers silently for all the members appearing after the macro. Nevertheless, it could be useful for RAD tools generating C++ source code.

I can only guess why you see that in human written classes. My guess is that it is poor coding; the writer probably wanted to express that a chunk of data belongs together and / or wanted to be able to move up and down those chunks within the class definition, together with the corresponding access modifier (private/protected/public).

Answer 2

I'll go one step farther from my comment for this answer, with a snippet of code.

class myClass {

    // initializers etc
    public:
        myClass();
        ~myClass();

    // signal processing
    public:
        void modifyClass();
    private:
        float signalValue;

    // other class responsibilities
    public:
        void doWork();
    private:
        void workHelper();
};

and so on. I wouldn't say this is a solid DESIGN for the class, but it's a good way to show the different capabilities of a class.