Global declaration?

This is a discussion on Global declaration? within the C++ Programming forums, part of the General Programming Boards category; If I define my own class in a header file as follows: Code: class tug{ public: int arraypos[3]; //other data ...

  1. #1
    Funniest man in this seat minesweeper's Avatar
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    Global declaration?

    If I define my own class in a header file as follows:

    Code:
    class tug{
    public:
    int arraypos[3];
    //other data members
    } usertug,cputug;
    Are usertug and cputug effectively global variables and can i access usertug.arraypos[(subscript)] from anywhere in my header file and in my source file? (provided obviously that i #include my header in the source)

  2. #2
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    try it out...
    "The most common form of insanity is a combination of disordered passions and disordered intellect with gradations and variations almost infinite."

  3. #3
    Registered User InFeStEd-ArCh0n's Avatar
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    I don't believe so. You have to define a variable as your class and make sure it is above everything and not in a function.
    -Mike
    {InFeStEd-ArCh0n}

  4. #4
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    try this ...

    try using a pointer or reference, it might work out for you !

  5. #5
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    The answer is yes. If you declare a variable in a header file (outside of functions etc..) it will be global throughout the program. but if you want to use it in all your header files put the declaration before you #include em.
    "The most common form of insanity is a combination of disordered passions and disordered intellect with gradations and variations almost infinite."

  6. #6
    Funniest man in this seat minesweeper's Avatar
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    Thanks for your help guys. I have found though that it isn't whether it is possible to access the variables that is the problem. I have never had an explanation for the problem and if anyone could explain or even better point me to a tutorial that does explain it, that would be great. OK, basically I have some classes for my battleships game, one for each type of ship. They are some thing like this:

    Code:
    class tug{
    int nopos 2; //number of map positions it uses
    int arraypos[2]; //integer values of grid positions
    //other data members
    }usertug, cputug;
    
    class sub{
    int nopos 3; //number of map positions it uses
    int arraypos[3]; //integer values of grid positions
    //other data members
    }usersub, cpusub;
    
    //etc....
    I then created a template function for ship placement so that I could pass any of my ships into it to be positioned on the grid.

    The function was:
    Code:
    template <class T>
    T placeship(T aship....etc..)
    {
    //code to place ship
    }
    However, within the template function, I found that although when I used for example aship.nopos, and passed in usersub, the value was correctly 3. But when I tried to for example write aship.arraypos[0]=value, the value was never put into the array.

    Any help on this topic would be gratefully received as I have not found it in any tutorials and it has not been taught to us at university.

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