Quit the whole program early in C?

Question

Generally say I have some functions step1 step2 ... and they are called successively:

int main()
{
  ...
  step1();  // something wrong detected and need to break out of the whole program
  step2();
  step3();
  ...
}

How can I break out from step1 and skip all the rest of code to terminate main() function?

Currently I can only think of setting a global variable like bool isErr as a flag so that

step1();  // error detected and isErr is set to 1 inside step1()
if (isErr)
  return;
step2();
...

Are there better or more 'canonical' approaches?

BTW I've heard that goto is bad so I discard it :)

possible duplicate of [How to quit a C++ program?](http://stackoverflow.com/questions/1116493/how-to-quit-a-c-program) — usr1234567, Sep 26 '15 at 13:06
If the problem is because of some data flow that you would like the user to be able to inspect, `std::abort()` may be a good idea, since it exits the process with a signal and may cause the host to create a core dump (making the situation debuggable in multiple ways). — Kerrek SB, Sep 26 '15 at 13:06

score 7 · Answer 1 · answered Sep 26 '15 at 13:04

7

Use

exit(1);

The number indicates the exit status. 0 is no failure, everything larger then 0 indicates an error.

answered Sep 26 '15 at 13:04

usr1234567

21,601
16
108
128

2

The only portable return values in C are `EXIT_SUCCESS` and `EXIT_FAILURE` (but not `1`). – Kerrek SB Sep 26 '15 at 13:05
1

EXIT_FAILURE is defined as 1 – Mar 21 '17 at 09:24

score 5 · Accepted Answer · edited May 23 '17 at 11:51

One option is to check return value of your step1() function and if it is error, just use for example return 1 in main. Using return (with appropriate status code) from main to finish the program is the preferred way in C++.

Other option is exit. The point is you can call it anywhere in the code. However, in C++ exit is not recommended that much. Regarding C, there is a question here which discusses whether using exit in C is a good idea or not.

score 1 · Answer 3 · answered Sep 26 '15 at 13:03

1

You can use the exit() function to terminate the process at any point during step1(), step2()... anywhere actually.

answered Sep 26 '15 at 13:03

chqrlie

131,814
10
121
189

score 1 · Answer 4 · answered Sep 26 '15 at 13:04

1

exit will terminate the program from wherever you are, but in most cases this is a bad idea, checking the return value of a function and handling (e.g. exit in your case) is a cleaner way to do it (no need for globals)

answered Sep 26 '15 at 13:04

MByD

135,866
28
264
277

Quit the whole program early in C?

4 Answers4