How to exit a console app in C using switch case?

Question

For example, if I made a simple switch-case how would I make the console app close depending on the input? I don't want to use to use break; and skip the loop, I want to close the console altogether.

char choice; 

printf("Run random function \n");
printf("Exit \n");

choice = getchar();
fflush(stdin);

switch(choice)
{

            case '1':
                 //randomFunction();

            case '2':
                 //I want this case to exit the console the console
}

@GrijeshChauhan Much worse: it is undefined behavior! For example see [here](http://stackoverflow.com/questions/2979209/using-fflushstdin) — LorenzoDonati4Ukraine-OnStrike, Aug 31 '13 at 16:43
@LorenzoDonati Its undefined on Unix based system but [some compilers provide the use of `fflush(stdin)` as an extension](http://stackoverflow.com/questions/17827603/scanf-wont-execute-for-second-time/17827635#17827635) — Grijesh Chauhan, Aug 31 '13 at 16:55
@GrijeshChauhan I don't agree on the terminology: this is still undefined behavior according to the standard. The fact that some implementation makes it documented doesn't change its status vs. the standard. An implementation could also document **its** behavior when you dereference a dangling pointer, but this still UB according to the standard, in other words a program using that extension is, by definition, nonportable. — LorenzoDonati4Ukraine-OnStrike, Aug 31 '13 at 17:05
@GrijeshChauhan The concept of UB is not related to Unix systems or to whatever environment/implementation you are using, it is a concept related to C language standards. See also [this](http://stackoverflow.com/questions/18420753/unspecified-undefined-and-implementation-defined-behavior-wiki-for-c/18420754#18420754) — LorenzoDonati4Ukraine-OnStrike, Aug 31 '13 at 17:06
@LorenzoDonati: The behaviour of `fflush(stdin);` is undefined according to the C standard, but implementations are free to add extensions to the standard (else Linux is horribly, horribly non-standard). Microsoft has chosen to make `fflush(stdin)` defined; if you are using Microsoft's C runtime library, it is legitimate to consciously use the extension. — Jonathan Leffler, Aug 31 '13 at 22:03
If you don't use `break`, when the `randomFunction();` returns, your program is going to exit (once you've got that part sorted out). Inside a `switch` statement, using `break` is normal, sane, expected; not using `break` is abnormal, insane, unexpected. — Jonathan Leffler, Aug 31 '13 at 22:12
@JonathanLeffler Yes, I knew about extensions. I only argued about terminology. If it is a conscious decision, well that's ok (I'm not arguing against it at all), but I only wanted to highlight that relying on extensions make a program (according to the standard) nonportable, and I doubt that newbies use `fflush(stdin)` with such a consciousness. Anyway thanks for the tip about `fflush(stdin)` being defined by the MS C runtime (didn't know that). I guess this means that I could use it inside programs compiled with MINGW-GCC without invoking UB then. — LorenzoDonati4Ukraine-OnStrike, Aug 31 '13 at 22:20
I had no idea using `fflush(stdin)` was so bad.. I read it in a book to use for windows/OSX and `fpurge(stdin)` for unix like systems. Thanks for the extra help. @LorenzoDonati I will now read the link you posted so I can find something better to use - possibly not using `getchar()` at all? — Ali Appleby, Sep 01 '13 at 15:16

score 1 · Answer 1 · edited Aug 31 '13 at 21:51

1

Simply use exit (EXIT_SUCCESS);

Ref -exit

edited Aug 31 '13 at 21:51

answered Aug 31 '13 at 16:16

P0W

46,614
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This works perfectly, thank you so much! Sorry for asking a random question, I tried searching for ages for but I only found results for c++ or c# – Ali Appleby Aug 31 '13 at 16:28

Edward Clements · Accepted Answer · 2013-08-31T16:31:31.500

0

You could call exit() passing the return value as a parameter, this return value can be checked by the calling process / batch file:

exit(EXIT_SUCCESS); // = 0 = (standard) success

or

exit(EXIT_FAILURE); // = 1 = (standard) failure

or

exit(123); // return a specific value

Documentation for MS-Visual Stuidio

edited Aug 31 '13 at 16:31

answered Aug 31 '13 at 16:15

Edward Clements

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How to exit a console app in C using switch case?

2 Answers2