Re: [Dev-C++] 'extern const' and std::vector

[David M. <ci...@ya...>]

MessageI think I better explain my current position. I am helping create a MMORPG. The vector is going to be used for access to the rooms. The current room system uses vnums (each rooms is assigned a vnum which is used to access it, another reason for my choice of vector). exits to other rooms just refrence the vnum and the code knows exactly what room to put the user in. For this reason a sequence container seems to be my only option. The same system is used for the objects and mobiles (characters that are not players).  ----- Original Message -----   From:   Ioannis   Vranos   To: dev...@li...     Sent: Thursday, May 01, 2003 11:02   AM  Subject: RE: [Dev-C++] 'extern const' and   std::vector  
  -----Original Message-----
From: dev...@li...   [mailto:dev...@li...] On Behalf Of David   McKen
Sent: Thursday, May 01, 2003 4:10 PM
To: dev...@li...
Subject:   [Dev-C++] 'extern const' and std::vector

      My first question concerns the extern     keyword.         If I have a varible in one file (it is not a     constant) but that varible needs to accessed from the functions in another     file. However these other functions do not need (actually I don't want them     to have) write access to this variable, can I do something similar to 'const     <var_type> <var_name>?'. For those of you who are wondering why     I don;t just try it myself I would like to know what EVERY ANSI compatible     compiler will do. The program I am writing must remain portable.          You do not specify language. That creates extra pain. In C   & C++ yes you can do extern const int x; In C++ you have better use a   namespace.         My other question concerns the std::vector     container class of the STD.         As far as I have seen the std:vector class     stores it's contents contiguously in memory (just like an array). Does this     make vector classes reach their maximum size once there is no block of     memory big enough to hold it's data?        You haven't to worry about   these details. It is an implementation worry and in reality the vector is just   a handler interface. That's why the vector::swap()  works instantly.   Also you can specify for it your own memory allocator. But handlers and   allocators are advanced magic for me yet so i can't tell you more on that   till i end TC++PL3. :)        In any case you have not to   worry about these details.                 I plan to use this class to act as     the index for world system with up to 2^32 rooms in it (even if I store only     pointers to each structure it still gets pretty big). Would any of the other     containers be better suited to this purpose? I chose the vector bacause of     it's speed (4 billion possible rooms, gonna need the speed). The     requirements for the container is to allow for a numbering system for eah of     the rooms with rooms being grouped within ranges.      Regarding constant random access with []   time cost: vector, deque, string, valarray and bitset have   this.        Reference for all the time costs for all   containers for all types of access ([], front operations,   etc):     "The C++ Programming Language" 3rd Edition or   Special Edition by Bjarne Stroustrup (the creator of   C++):     On page   464.                Ioannis Vranos

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