[C++] In main() , return 0 problems

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1.00/5 (1 vote)

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int main()
{
    .......
    return 0;
}

As we know, return 0; is used for terminating a program. But where is the value returns to ??
Please help me with this silly question. Thank you =]

Posted 24-May-11 0:38am

Mario To

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Legor 24-May-11 7:15am

both answers below are right. please exaccept one (or more) of the solutions.

Marc A. Brown 24-May-11 14:21pm

Legor is correct. All 3 answers are good. Please accept at least one of them, perhaps even all of them, as the correct (accepted) answer(s).

3 solutions

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CPallini · Accepted Answer · 2011-05-24T00:53:00

Solution 1

To the Operating System.
See, for instance, how can you see such return value on Windows (courtesy of 'the competitors'...):"how do I get the application exit code from a Windows command line[^] at StackOverflow.

Posted 24-May-11 0:53am

CPallini

Comments

Sergey Alexandrovich Kryukov 24-May-11 14:05pm

Correct, but...
The answer is so simple, please see mine.
--SA

Marc A. Brown 24-May-11 14:20pm

Good answer!

Joan M · Accepted Answer · 2011-05-24T00:59:00

Solution 2

Read this[^]...

Those return values are used to know the exit status of an app... (i.e. you could call an app from yours and you could be interested on knowing how has it finished).

HTH! :thumbsup:

Posted 24-May-11 0:59am

Joan M

Comments

Sergey Alexandrovich Kryukov 24-May-11 14:06pm

Correct, good reference, my 5.
I simply pot short complete answer, please see.
--SA

Joan M 25-May-11 2:08am

Thank you SAKryukov!

love_small 25-May-11 9:18am

where i can see?

Joan M 25-May-11 9:23am

I guess you wanted to originally post to SAKRyukov... and that at the beginning you've posted to me... Anyway, you can see his post a little bit forward in that same page. (SOLUTION 3). ;)

Marc A. Brown 24-May-11 14:20pm

Great answer. My 5.

Joan M 25-May-11 2:08am

Thank you Marc!

Albert Holguin 24-May-11 14:28pm

my 5, partially because you're right... and partially because you've allowed me to use lol

Joan M 25-May-11 2:09am

Thank you Albert! partially for your comment, partially for your vote and partially because it is deserved... :-D

Espen Harlinn 24-May-11 19:40pm

Nice reply, my 5

Joan M 25-May-11 2:10am

Thank you Espen!

Sergey Alexandrovich Kryukov · Accepted Answer · 2011-05-24T08:05:00

Solution 3

No! Return 0 is not used to terminate a program! Who told you so?

The return value is called exit code.

On Windows, exit code value can be examined by batch file or a code in parent process (via Windows API CreateProces or CreateProcessEx) after the application is closed.
(Thanks to C Pallini for pointing out that this is applicable to Windows only; I forgot to mention it.)

In other system (at least all Unix-like ones and other Posix-based which includes Windows), the exit code can also can be examined by the command interpreters and the parent processes in general. Traditionally, 0 is used to indicate "no problem", "success", but the exit code can mean anything at all, this is application-specific. In present-day practice, used rarely.

That's all you need to know about it.

—SA

Posted 24-May-11 8:05am

Sergey Alexandrovich Kryukov

Updated 24-May-11 9:36am

v3

Comments

Albert Holguin 24-May-11 14:11pm

as always, very informative... but as a batch builder, please let that mean something in your apps! :)

Sergey Alexandrovich Kryukov 24-May-11 14:17pm

Thank you Albert.
I feel you want to say something interesting about a batch builder... but what exactly do you mean?
Practically, I think MSBuild can do everything in declarative manner and it the batch approach should be avoided. I learned to write highly customized MSBuild projects manually and know it has absolute power. You only need batch file to short-cut the call to MSBuild with parameters itself.

Albert Holguin 24-May-11 14:21pm

I mean creating batch files to accomplish something outside of the app, for example, I have an automatic build script that checks if anyone has checked in crappy code onto the server... in a similar fashion, if I were using software you built and I needed to run it in conjunction with other software via some sort of batch that was controlling the process, it'd be nice to have feedback to make sure everything executed correctly without errors... my automatic build script will e-mail me if there's errors in the process, it sits in a server in a back room.

Sergey Alexandrovich Kryukov 24-May-11 15:40pm

Yes, sure. Then again, I maintain it is not very much needed as MSBuild covers all the needs; and you can use/embed any other console applications or write a special MSBuild task assembly DLL.

That said, exit code can be used with MSBuild as well, as with any other applications capable of getting the exit code from a terminated child process.
--SA

Albert Holguin 24-May-11 15:51pm

msbuild only relates to builds though, what about just coordinating processes...

Sergey Alexandrovich Kryukov 24-May-11 22:54pm

Well, build can be considered wider.... :-) You can actually use MSBuild as a declarative "batch" shell. But don't get me wrong, I use regular batches, for some purposes extensively.
--SA

Marc A. Brown 24-May-11 14:20pm

Excellent answer as always.

Sergey Alexandrovich Kryukov 24-May-11 15:37pm

Thank you Marc. (Updated thanks to a note by C Pallini.)
--SA

CPallini 24-May-11 15:28pm

My 5. Just a note: you're assuming Windows OS usage, anyway there's no mention of Windows in the OP.

Sergey Alexandrovich Kryukov 24-May-11 15:32pm

Thank you very much.
Thanks for your note: I really need to add this note to the answer.
--SA

Espen Harlinn 24-May-11 19:39pm

Good effort, my 5

Sergey Alexandrovich Kryukov 24-May-11 20:53pm

Thank you, Espen.
--SA

Mario To 25-May-11 6:06am

Thank you for correcting my wrong concept of return 0...
And thanks for your helps!

Sergey Alexandrovich Kryukov 25-May-11 8:50am

My pleasure.
Thanks for accepting this answer.

Good luck, call back,
--SA