RE: [Dev-C++] #DEFINE versus cont variables in array inicializations

[Ioannis V. <iv...@te...>]

> -----Original Message-----
> From: Per Westermark [mailto:pw...@ia...] 
> Sent: Saturday, May 31, 2003 3:18 AM
> To: Ioannis Vranos
> Cc: Dev-C++ Mailing List
> Subject: RE: [Dev-C++] #DEFINE versus cont variables in array 
> inicializations
> 
> 
> Give a declaration:
> 
>   const int SIZE = 7;
> 
> If you don't take the address of it, the compiler will generate code
> looking like:


It is difficult for the compiler to know if I use its address in another
file. Usually the linker notices the uses in other files.



> 
>   pushl $7
> 
> If you take the address of it, the compiler will notice and 
> generate code
> like:
> 
>   pushl $_SIZE
> 
>   ...
> 
>   _SIZE:
>     .long 7
> 
> where the second case will store _SIZE in .text and not in .data.


I can't understand the above very much but I do not think the compiler cn
check every file for this, only the linker. Also what if I make obj files
and then add some code in a cpp file that uses the address, make a new obj
annd then link all objs together?


 
> You will be able to take the address of SIZE from one object 
> file. If you
> declare 'const int SIZE = 7;' in another file to and try to take the
> address of it, you will correctly get a linker error. If you 
> in the other
> file declares 'extern const int SIZE', that file will always 
> reference the
> variable SIZE, since it can't do any inlining.



This is a bit difficult. You know, extern const int SIZE; is a *definition*
in the absense of another definition and takes the default value 0.




Ioannis Vranos
 
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