Thread: A simple question about scope

  1. #1
    external validation
    Join Date
    Dec 2004
    Posts
    9

    A simple question about scope

    Hi, this is my first post.

    It concerns the scope of a loop control counter object declared inside the for statement...

    Here is an example:
    Code:
    {
       statement;
       ...
       statement;
       // let's call this "SCOPE 1"
       // now...
       for (int i=1; 1<=10; i++)
       {
          statement;
          ...
          statement;
          // let's call this "SCOPE 2"
       }
       statement;
       ...
       // now we're back to "SCOPE 1"
    }
    Could someone (well, ideally many people) tell me whether the scope of i (as declared inside the for statement) is SCOPE 1 or SCOPE 2 ?

    Much obliged,
    Doug.
    Last edited by dwylie; 12-10-2004 at 01:14 PM.

  2. #2
    Gawking at stupidity
    Join Date
    Jul 2004
    Location
    Oregon, USA
    Posts
    3,218
    Why don't you just try it?
    If you understand what you're doing, you're not learning anything.

  3. #3
    Yes, my avatar is stolen anonytmouse's Avatar
    Join Date
    Dec 2002
    Posts
    2,544
    Welcome to the forums!

    In C89 variables must be declared at the start of a block. That is, after a { and before other statements. In C99 and C++ compilers, one of which you must be using, you can declare variables elsewhere. You should be aware that not all compilers imlement C99 yet. A variable declared in the initializer of a for loop will have scope only in the for block. That is "Scope 2" in your example. It will not be visible in "Scope 1". You can easily test scope by trying to use a variable in the different scopes. Your compiler will trigger an error if the variable is not visible.

    Please consider reading this post.

  4. #4
    external validation
    Join Date
    Dec 2004
    Posts
    9

    thanks for the advice

    Right ho.
    I put in the code tags and I am away to start an X-session and learn by experimentation
    D.

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