'm_dlgColor' : undeclared identifier in B.cpp error....

This is a discussion on 'm_dlgColor' : undeclared identifier in B.cpp error.... within the C++ Programming forums, part of the General Programming Boards category; Hey, Good day. In my project. A.h Code: ... Public: COLORREF m_dlgColor; ... A.cpp ...... B.h ... B.cpp Code: #include ...

  1. #1
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    'm_dlgColor' : undeclared identifier in B.cpp error....

    Hey,

    Good day.


    In my project.

    A.h
    Code:
    ...
    
    Public:
    
    COLORREF     m_dlgColor;
    
    ...
    A.cpp
    ......

    B.h
    ...
    B.cpp
    Code:
    #include "A.h"
    
    ...
    
    m_dlgColor = RGB(90,90,90);
    
    ...

    I already declared m_dlgColor as a public propertise. and i also include A.h to my B.cpp.
    Why i can't compile the project successful ?

    Thanks!

    Novice's question. :-)
    Last edited by userpingz; 06-08-2009 at 09:35 PM. Reason: prject -> project
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  2. #2
    and the Hat of Guessing tabstop's Avatar
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    A member of a class is just that: a member. It doesn't exist on its own, but only as part of a ... whatever you defined it as part of.

  3. #3
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    As you said,
    Does i should declare "COLORREF m_dlgColor;" at B.h too?

    Suppose, when i changed A.cpp class member - m_dlgColor value to (200, 200, 200). I still want to change B.cpp class member - m_dlgColor value to (200, 200, 200) synchronized.

    Then, how?

    thanks!
    --------------------------------------------------------
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  4. #4
    and the hat of wrongness Salem's Avatar
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    Colour of what?

    You need something like this.
    Code:
    class foo {
    Public:
    
    COLORREF     m_dlgColor;
    };
    And you need an OBJECT instance of some sort

    Code:
    foo aThingamajig;
    before you can do
    Code:
    aThingamajig.m_dlgColor = RGB(90,90,90);
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  5. #5
    and the Hat of Guessing tabstop's Avatar
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    Let's think about classes again:
    Code:
    class bob {
        public:
            int m_int;
            void bob_function(void);
    };
    Given this class, there is no possible way that "m_int" by itself could ever possibly be correct, except inside the member function bob_function. Everywhere else, it must be object.m_int.

  6. #6
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    i guess i already understand what you said. thanks!
    And furthermore questions.

    A.h
    Code:
    Public:
    COLORREF   m_dlgColor;
    // declare the member at head file.

    A.cpp
    [code]
    class ObjectA {
    public:
    int m_intA;
    // Q1, What's the different Or reason, if i declare member of "m_dlgColor" here ?
    void bob_functionA(void);
    };



    B.h
    Code:
    Public:
    COLORREF   m_dlgColorObjectB;
    B.cpp
    Code:
    class ObjectB {
        public:
            int m_intB;
            void bob_functionB(void);
            {
             // Q2: try to initialization Or Asign value via the following statement ?
             m_dlgColorObjectB = ObjectA.m_dlgColor
            }
            
    };
    Q3. Does the bob_functionB() Could be filled outside of Class ObjectB? What's the different between fill the member function inside the class or outside of the class?

    :-)
    Last edited by userpingz; 06-08-2009 at 09:59 PM. Reason: bold font for the question items
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  7. #7
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    Quote Originally Posted by Salem View Post
    Colour of what?
    My windowns forms application skin color changed....
    --------------------------------------------------------
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    Except for an idea put into action.
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  8. #8
    and the Hat of Guessing tabstop's Avatar
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    Neither of your questions make any sense. We declared our ints in the same place, so asking the difference based on where they're located isn't meaningful. And of course you can never assign anything inside a class definition -- you don't have any objects to assign values to. You initialize values in the constructor.

  9. #9
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    Really stupid questions.

    i am appricated for you patient. :-)

    Thanks a lot.
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    Except for an idea put into action.
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