Ananth A wrote:
>On 4/7/06, Jayasimha Ananth <jayasimha.a at gmail.com> wrote:
>
>
>>What is a conditional compiler?
>>
>>
>
>TurboC and MSVC++ uses this feature of compiling only the changed part
>instead of recompiling/linking the whole source code. Gcc/G++ on the
>other hand doesnt keep track of the changes and ends up compiling
>everything again. this is good for batch compilation but not so good
>for frequent compilations. you can test by making just 2-3 line
>changes in your code and recompiling it. tc/msvc would finish
>compiling almost instantly than gcc/g++ would.
>
>
There are three things that you seem to imply here: 1) Compiling just the
changed files as opposed to compiling all the source files; 2) Compiling
parts of changed files as opposed to compiling all the files; 3) Pre-
compiled headers.
As for #1, it is the normal behavior even on *NIX systems if you have the
Makefiles set up properly. Make takes care of tracking file modifications
and invokes gcc for only the changed files.
As for #2, I am not sure whether Tc or MVC does this, but maybe this is
done at the function level.
#3 is supported by gcc with the appropriate options.
Technically the term conditional compilation applies to preprocessor
directives that control which source lines are processed by the
compiler.
>btw, on a slightly off topic, g++ compiles much slower than gcc. at
>least 2-3x slower.... you can test it even with a simple program of
>printf("hello world") ... im using the 4.0.1 version and the same c
>code with both gcc and g++ for testing. has anybody else noticed the
>same ??
>
>
Yeah C++ compilation is always slower due to overheads. Have you tried
adding extern "C" for you hello world program to force C linkage and
disable the C++ poly-mangled-virtual-inherited-temporarily-constructed-
referential overheads ? I dunno whether this will help though. :-P
Regards,
Moinak.
>just noticed on the sun studio website that there is a version
>released for linux also... has anyone tried it ?? any comments ??
>
>Ananth
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