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Thread: static

  1. #1
    Join Date
    Mar 2009
    Posts
    82

    static

    Code:
    #include <iostream >
    using namespace std;
    
    class CL
    {
          public:
                 int x;
               static int y;
    };
    int CL :: y=2;
    
    int main()
    {
    
    return 0;
    }
    Why I can't write it like?

    Code:
    #include <iostream >
    using namespace std;
    
    class CL
    {
          public:
                 int x;
               static int y=2;
    };
    
    
    int main()
    {
    
    return 0;
    }

    And why in local classes (like class declared in function) I can't use static variables?

    Thanks in advance.

  2. #2
    Join Date
    Feb 2002
    Posts
    4,640

    Re: static

    C++ doesn't support initializing non const variables in a class declaration. I believe that may change with the next iteration of the C++ standard.

    Viggy

  3. #3
    Lindley is offline Elite Member Power Poster
    Join Date
    Oct 2007
    Location
    Fairfax, VA
    Posts
    10,885

    Re: static

    const static integers (and related types) may be initialized inline for now.

  4. #4
    Join Date
    Mar 2009
    Posts
    82

    Re: static

    Thanks for the help. But why it isn't possible? What's the problem?

    Thanks in advance.

    I got another question. Why I can't use variables other then static variables in static functions?

  5. #5
    Join Date
    Apr 2009
    Location
    Netherlands
    Posts
    91

    Re: static

    Quote Originally Posted by StGuru View Post
    Thanks for the help. But why it isn't possible? What's the problem?

    Thanks in advance.
    Because it isn't

    I got another question. Why I can't use variables other then static variables in static functions?
    Because that doesn't make any sense at all. You first need to make a instance of the class to be able to call its non-static member functions or use its non-static variables. A class is just a template to create objects from, nothing actually exists yet until you make an instance. This is why static content can always only interact with other static content.
    Last edited by AlastrionaAdair; April 30th, 2009 at 12:39 PM.

  6. #6
    Join Date
    May 2009
    Posts
    3

    Re: static

    Quote Originally Posted by StGuru View Post
    I got another question. Why I can't use variables other then static variables in static functions?
    The response above this pretty much sums it up. As soon as you understand what a static member variable/function is, the answer is self-evident. When you declare a member of a class static, you're essentially making it global. Whatever you declare static is going to be the same no matter where in the program you access it from; there's one copy of it.

    The class within which you declare it is instantiated as an instance (an object), of which there can be multiple copies. The static member is singular. Therefore, it doesn't make any sense to try to reference something nonstatic within a static context.

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