C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  what is file scope?          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Vipul Jain Guest Posted: Sat Sep 25, 2004 9:17 pm    Post subject: what is file scope? Can any one please tell me what is the difference between global scope of an variable and file scope of an variable. Vipul Back to top Victor Bazarov Guest Posted: Sun Sep 26, 2004 1:08 am    Post subject: Re: what is file scope? "Vipul Jain" <vipulsj (AT) yahoo (DOT) com> wrote... Quote: Can any one please tell me what is the difference between global scope of an variable and file scope of an variable. None whatsoever. Back to top E. Robert Tisdale Guest Posted: Sun Sep 26, 2004 1:13 am    Post subject: Re: what is file scope? Vipul Jain wrote: Quote: Can any one please tell me what is the difference between global scope and file scope of an variable. cat file.cc int a = 0; // global scope static int b = 0; // file scope Back to top Unforgiven Guest Posted: Sun Sep 26, 2004 4:39 pm    Post subject: Re: what is file scope? "E. Robert Tisdale" <E.Robert.Tisdale (AT) jpl (DOT) nasa.gov> wrote Quote: Vipul Jain wrote: Can any one please tell me what is the difference between global scope and file scope of an variable. cat file.cc int a = 0; // global scope static int b = 0; // file scope I don't agree with that. The way I was tought it scope deals only with visibility of a name in code. Without extra help (an extern declaration), "a" is visible only within the translation unit file.cc, so it has file scope. As such, true global scope doesn't exist in C++, and the term global scope is frequently used to refer to file scope. So as Victor said, there is no difference. According to the terminology I know, "a" has external linkage and "b" has internal linkage, but they both have the same scope (file) and lifetime (application). -- Unforgiven Back to top David Harmon Guest Posted: Sun Sep 26, 2004 5:04 pm    Post subject: Re: what is file scope? On Sat, 25 Sep 2004 18:13:16 -0700 in comp.lang.c++, "E. Robert Tisdale" <E.Robert.Tisdale (AT) jpl (DOT) nasa.gov> wrote, Quote: Vipul Jain wrote: Can any one please tell me what is the difference between global scope and file scope of an variable. cat file.cc int a = 0; // global scope static int b = 0; // file scope Sorry, there is no difference in scope between those two. The names "a" and "b" are both introduced into the scope in which the declarations occur. In a namespace scope (including the global namespace scope), those declarations illustrate the difference between internal linkage and external linkage. In a block scope, those declarations illustrate the difference between automatic storage duration and static storage duration. I think Victor had the correct answer. Back to top E. Robert Tisdale Guest Posted: Sun Sep 26, 2004 10:49 pm    Post subject: Re: what is file scope? David Harmon wrote: Quote: E. Robert Tisdale wrote: Vipul Jain wrote: Can any one please tell me what is the difference between global scope and file scope of an variable. cat file.cc int a = 0; // global scope static int b = 0; // file scope Sorry, there is no difference in scope between those two. The names "a" and "b" are both introduced into the scope in which the declarations occur. In a namespace scope (including the global namespace scope), those declarations illustrate the difference between internal linkage and external linkage. In a block scope, those declarations illustrate the difference between automatic storage duration and static storage duration. I think Victor had the correct answer. I'm sure that you and Victor have the correct answer to some question but I don't think that was the distinction that Vipul Jain was looking for. Back to top Victor Bazarov Guest Posted: Mon Sep 27, 2004 1:11 am    Post subject: Re: what is file scope? "E. Robert Tisdale" <E.Robert.Tisdale (AT) jpl (DOT) nasa.gov> wrote... Quote: David Harmon wrote: E. Robert Tisdale wrote: Vipul Jain wrote: Can any one please tell me what is the difference between global scope and file scope of an variable. cat file.cc int a = 0; // global scope static int b = 0; // file scope Sorry, there is no difference in scope between those two. The names "a" and "b" are both introduced into the scope in which the declarations occur. In a namespace scope (including the global namespace scope), those declarations illustrate the difference between internal linkage and external linkage. In a block scope, those declarations illustrate the difference between automatic storage duration and static storage duration. I think Victor had the correct answer. I'm sure that you and Victor have the correct answer to some question but I don't think that was the distinction that Vipul Jain was looking for. I suppose you have a working crystal ball then, since you definitely knew that the OP wanted to know about linkage and not scope. I just can't imagine that it was you who confused them... V Back to top E. Robert Tisdale Guest Posted: Mon Sep 27, 2004 1:27 am    Post subject: Re: what is file scope? Victor Bazarov wrote: Quote: I suppose you have a working crystal ball then, since you definitely knew that the OP wanted to know about linkage and not scope. I knew no such thing. But I do know what C and C++ programmers usually mean when they say "global scope" and I think that you do too. Quote: I just can't imagine that it was you who confused them... Oh, let's just pretend that I'm confused and *not* Vipul Jain. Please elaborate for *me* the difference between scope and linkage. Back to top Victor Bazarov Guest Posted: Mon Sep 27, 2004 2:09 am    Post subject: Re: what is file scope? "E. Robert Tisdale" <E.Robert.Tisdale (AT) jpl (DOT) nasa.gov> wrote... Quote: Please elaborate for *me* the difference between scope and linkage. Get a copy of the Standard and study it. Back to top David Harmon Guest Posted: Mon Sep 27, 2004 4:48 am    Post subject: Re: what is file scope? On Sun, 26 Sep 2004 18:27:57 -0700 in comp.lang.c++, "E. Robert Tisdale" <E.Robert.Tisdale (AT) jpl (DOT) nasa.gov> wrote, Quote: Please elaborate for *me* the difference between scope and linkage. An identifier that can be referred to as ::identifier is in the global scope (AKA global namespace scope.) You have already shown how such an identifier can have internal or external linkage. 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