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

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

At first the const reference can't be used for the size of the array, my
mistake.



For the rest, I do not get your point:


int main()
{
	int array[17];

}


g++ -pedantic-errors -Wall -fexpensive-optimizations -O3 -ffloat-store
-mcpu=pentiumpro temp.cpp -o temp


29/05/2003  11:09 ??            23.036 temp.exe



For the code:

int main()
{
 const int SIZE=17;

 int array[SIZE];

}


29/05/2003  11:10 ??            23.036 temp.exe


So the compiler optimises out the const int thing.



Ioannis Vranos
 
* Programming pages: http://www.noicys.freeurl.com
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* Alternative URL 2: http://www.noicys.cjb.net




> -----Original Message-----
> From: Per Westermark [mailto:pw...@ia...] 
> Sent: Friday, May 30, 2003 2:00 AM
> To: Ioannis Vranos
> Cc: Dev-C++ Mailing List
> Subject: RE: [Dev-C++] #DEFINE versus cont variables in array 
> inicializations
> 
> 
> I guess you don't think of gcc as a decent compiler then.
> 
> try gcc -O3 -S on the code below and look at the output.
>   4 byte for the value 7
>   4 byte for the SIZE reference.
>   access loads SIZE and pushes [SIZE] (4 byte addr info + extra instr)
> 
> with const int SIZE = 7
>   zero byte for value
>   every access pushes 7 directly. (4 byte value)
> 
> Most compilers treat 'const int v = <value>' identical to #define XX
> <value>, i.e. optimal code is generated.
> 
> /Per W
> 
> On Thu, 29 May 2003, Ioannis Vranos wrote:
> 
> > A third way that guarantees no space occupation by a decent 
> compiler is:
> >
> >
> > const int &SIZE = 7;
> >
> >
> >
> >
> >
> >
> > Ioannis Vranos
> >
> > * Programming pages: http://www.noicys.freeurl.com
> > * Alternative URL 1: http://run.to/noicys
> > * Alternative URL 2: http://www.noicys.cjb.net
> >
> >
> >
> >
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