CODEWITHSUNDEEP
c++
Robin
Robin

Reputation: 737

How to access member variables, from non member function within class C++

I have created a class called "ShortestTime". I have some functions within it that are not member functions, but I would like them to be able to access my member variables.
ie. I have a function that sorts a List that is a public member variable, but it doesn't have access to this member variable.

I have read something about "friend" but was unable to get this to work. How do I solve my problem?

Thanks for the help,

Robin

Upvotes: 0

Views: 7393

Answers (3)

Tony Delroy
Tony Delroy

Reputation: 106246

I have created a class called "ShortestTime". I have some functions within it that are not member functions, ...

No you don't :-). All the functions within a class are member functions by definition. You might well have some functions without the class - they would not be member functions.

but I would like them to be able to access my member variables. ie. I have a function that sorts a List that is a public member variable, but it doesn't have access to this member variable.

Yes it does. You've said you have a public member variable List:

class X
{
  public:
    List identifier_;
};

All functions have access to the list, irrespective of whether they're member functions or not.

I have read something about "friend" but was unable to get this to work. How do I solve my problem?

The only situation in which you might find you need friend, and hence the one that might apply despite the statements above, is akin to...

class X
{
  public:

  private:
    List identifier_;
};

void some_non_member_function()
{
    X x;
    x.identifier_;  // HOW TO GET ACCESS...?
}

To grant some_non_member_function() access to a private data member, you can...

make it a friend of the class

class X
{
    friend void some_non_member_function();
};

void some_non_member_function()
{
    X x;
    x.identifier_;  // NOW OK
}

make it a member function

class X
{
  public:
    void some_non_member_function()
    {
        X x;
        x.identifier_;  // NOW OK
    }
};

Upvotes: 0

Munim
Munim

Reputation: 6520

It completely depends on what language we are talking about here. Since you are talking about "friend" functions, I am going to assume you are talking about c++. So basically, a friend function is just a normal function which has access to private and protected members of a class in c++. For example.. 

int abc(myclass a)    
{   
...   
}   
class myclass   
{   
    int someprivatemembers;   
    public:   
        function myClass() { ... }   
        friend int abc(myclass);   
}

Now, in the above example, the function abc will have access to someprivatemembers of object a passes to it, because it is declared as a "friend" of the class.

Upvotes: 0

madmik3
madmik3

Reputation: 6983

There are ways you could use friend to solve your problem but we would need to see sample code.

But my personal approach would be to add a function to ShortestTime that sorts your private member. 

ShortestTime::SortInterals()
{
   //sort private stuff
}

Is there a reason that won't work?

Upvotes: 2

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