Classes

This is a discussion on Classes within the C++ Programming forums, part of the General Programming Boards category; Hi there, I have a class within a class. How do I create an object of the sub class and ...

  1. #1
    Registered User
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    Nov 2006
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    Question Classes

    Hi there,

    I have a class within a class. How do I create an object of the sub class and then use it.

    eg)
    Code:
    class setA
    {
    protected:	
    	int Weight;
    	string Name;
    
    	void SetWeight(int Weight_in) { Weight = Weight_in; }
    	void SetName(string Name_in) { Name = Name_in; }
    
    public:
    	class part1
    	{
    	protected:
    		int DescentRate;
    		double MaxHeight;
    
    		void SetDescentRate(int DescentRate_in) { DescentRate = DescentRate_in; }
    		void SetMaxHeight(double MaxHeight_in) { MaxHeight = MaxHeight_in; }
    	};
    };

    How could I access and hence use setdescentrate() in the main???

    Thanks

  2. #2
    Registered User Codeplug's Avatar
    Join Date
    Mar 2003
    Posts
    4,702
    With the scope resolution operator, "setA::part1" is the full type name.

    gg

  3. #3
    Registered User
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    Quote Originally Posted by strokebow View Post
    Hi there,

    I have a class within a class. How do I create an object of the sub class and then use it.

    eg)
    Code:
    class setA
    {
    protected:	
    	int Weight;
    	string Name;
    
    	void SetWeight(int Weight_in) { Weight = Weight_in; }
    	void SetName(string Name_in) { Name = Name_in; }
    
    public:
    	class part1
    	{
    	protected:
    		int DescentRate;
    		double MaxHeight;
    
    		void SetDescentRate(int DescentRate_in) { DescentRate = DescentRate_in; }
    		void SetMaxHeight(double MaxHeight_in) { MaxHeight = MaxHeight_in; }
    	};
    };

    How could I access and hence use setdescentrate() in the main???

    Thanks

    Thanks for replying

    I thought that but it didnt and still doesnt work

    Code:
    void main(void)
    {
    
    	SetA::part1  x;
    
    	x.SetDescentRate(12);
    
    	
    
    }
    Gives an error.

    error C2248: 'SetA:art1::SetDescentRate' : cannot access protected member declared in class 'SetA:art1'

    Can anyhone explain? any ideas? explanations?

  4. #4
    Captain Crash brewbuck's Avatar
    Join Date
    Mar 2007
    Location
    Portland, OR
    Posts
    7,274
    Well, you can hardly expect to make something "protected" and then access it from a public context...
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

  5. #5
    Registered User
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    ha! sorry yeah

  6. #6
    C++まいる!Cをこわせ!
    Join Date
    Oct 2007
    Posts
    23,024
    As the error clearly outlines, the problem was not with creating an instance of the class, but calling a protected member function of that instance.
    You should learn to interpret error messages better.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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