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  #1  
Old 18-Jan-2009, 12:06
Sal Bruno Sal Bruno is offline
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How to access C++ data structure

I am new to C++ and need to know how to access (get/set or read/write) the prompt information from another module. Code and details to follow.

Module A.cc contains a data structure this:

CPP / C++ / C Code:

inode_state::inode_state(): parent (NULL), child (NULL), prompt ("%") {
}

Module A.h contains a data structure this:

CPP / C++ / C Code:

class inode_state {
   friend class inode;
   private:
      inode *parent;
      inode *child;
      string prompt;
   public:
      inode_state();
};
Last edited by LuciWiz : 18-Jan-2009 at 12:16. Reason: Corrected end [/cpp] tag
  #2  
Old 19-Jan-2009, 07:00
L7Sqr L7Sqr is offline
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Re: How to access C++ data structure

If you are using a class you do not have access to then you can not access the private members of that class (unless you are supplied a formal way to do so). If you had access to the class you could just implement getters/setters for the data. If not, the only other way to get at the data is to have it declared as protected in the base class and make your own class that is a sub class of inode_state.
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  #3  
Old 19-Jan-2009, 09:16
Sal Bruno Sal Bruno is offline
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Re: How to access C++ data structure

Apparently the "friend class inode" allows inode to see the private members of inode_state, but not the converse. Therefore, I was informed there is a way to have access to the prompt class member. Please let me know if this makes sense. Again, I am new to C++.
  #4  
Old 19-Jan-2009, 12:27
L7Sqr L7Sqr is offline
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Re: How to access C++ data structure

Lets start over.
What is it you are trying to do?
Do you have access to the inode_state class - i.e. can you edit its structure?
Do you have access to the inode class - can you edit its structure?

If can edit either of the above, it is a trivial task. Otherwise I'm not sure you will be able to do what you want (if I understand it correctly).
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  #5  
Old 19-Jan-2009, 14:33
Sal Bruno Sal Bruno is offline
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Re: How to access C++ data structure

Hello L7Sqr,

Thanks for being patient with me. I can access the inode_state and inode_class. I do not want to. So without change the .h and .cc files, how I update the prompt string member?
  #6  
Old 19-Jan-2009, 18:47
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Re: How to access C++ data structure

If you can access those classes, your best course of action (and most direct) is to edit the classes to do what you need. Otherwise you run the risk of confusing not only yourself but others who use your code.
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  #7  
Old 19-Jan-2009, 23:55
Sal Bruno Sal Bruno is offline
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Re: How to access C++ data structure

Hello L7Sqr,

I can edit the class. I need to add two function calls, a set and get. If the class in the module.h file was written in the following manner ...

CPP / C++ / C Code:
class exit_status {
   private:
      static int status;
   public:
      static void set (int);
      static int get();
};

With the code written in module.cc like this...

CPP / C++ / C Code:
void inode_state::set (string new_prompt) {
   prompt = new_prompt;
}
   
string inode_state::get() {
   return prompt;
}

How would I make the call in the main program to set and get the prompt?
Last edited by LuciWiz : 20-Jan-2009 at 01:35.
  #8  
Old 20-Jan-2009, 01:39
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LuciWiz LuciWiz is offline
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Re: How to access C++ data structure

Sal Bruno, please read the Guidelines from the link in my signature. The way you are trying to use code tags is wrong.

Thank you.
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