Re: entry point of application
* James Kanze:
On Nov 25, 4:33 pm, "Alf P. Steinbach" <al...@start.no> wrote:
[...]
The C++ standard requires a "main" startup function with "int"
result type.
The two signatures you show above must be supported.
With Microsoft tools you may indeed have to use the linker
option you referred to above, in order to correctly have the
standard "main" startup function called by the entry point
code.
Are you sure of this. I've only used VC++ for small, test
programs, but I've all of them have a fully standard main(), and
I'm not aware of having used any special compiler options to
make them link. (I have needed special options to get them to
compile C++. Including the standard library headers. But as
far as I know, things like /GR /Ehs /vmg or whatever don't
affect the linker.)
Yes, I'm sure.
I think your experience is due to mostly writing server-like code.
When you specify GUI subsystem (no automatic console window) the
Microsoft tools default to a different entry point that doesn't call
"main" but "WinMain". GNU tools are smart enough to pick the startup
function you provide. Microsoft's tools are not.
Specifying the entry point in order to have "main" called is
not, however, necessary with e.g. the GNU toolchain.
But you still need -std=c++98 if you want a C++ compiler:-).
(Admittedly, the differences are several orders of magnitude
less than if you forget /GR /Ehs /vmg when compiling with VC++.)
Well yes, sort of relevant. I didn't mention the corresponding option
for VC++ because with that option it fails to compile Microsoft's own
headers. Or at least used to, I haven't checked lately. :-)
It is unfortunate that a major compiler vendor still as of
late 2007 hasn't managed to correctly implement a feature from
1972 (going back to original C) so that you have to use linker
options, but then, that compiler defaults to non-standard
behavior also in many other respects: you have to use a load
of options to get standard-conforming mode (exceptions, RTTI,
for-loop scope, wchar_t).
Regretfully, that's the case for almost all compilers.
I think by "that" you're referring to the bunch of options I listed in
addition to specifying entry point. Well I have only limited experience
with current C++ compilers, but at least with g++ you don't have to
specify that basic functionality such as "main", exceptions, RTTI,
for-loop scope and built-in wchar_t, should be supported. It's one
thing to have to up warning levels or say hey, I want some extensions,
it's quite another thing to have specify in detail to a C++ compiler the
various aspects of the standard C++ language that you want supported.
And for those unfortunate newbies using that compiler via its associated
IDE, to have to turn off features such as Microsoft's precompiled
headers that cause non-standard behavior.
No options generally results in something that's barely usable.
Yes, no disagreement there!
And of course, you don't always want 100% standard-conformance.
(My professional code makes extensive use of sockets, threads
and a couple of other non-standard features.)
I have no experience with language extensions for sockets. Do they
really exist? Anyways, having to add in language extensions, or turn
them off, is as mentioned quite different from having to specify in
detail the aspects of the C++ language that you want supported.
Cheers,
- Alf
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