CODEWITHSUNDEEP
cterminate
mzoz
mzoz

Reputation: 1353

Quit the whole program early in C?

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 :)

Upvotes: 5

Views: 24707

Answers (5)

chux
chux

Reputation: 154562

Call exit(int status) anywhere in code.

Given various answers' discussions about status, let us look at the spec:

Finally, control is returned to the host environment.
If the value of status is zero or EXIT_SUCCESS, an implementation-defined form of the status successful termination is returned.
If the value of status is EXIT_FAILURE, an implementation-defined form of the status unsuccessful termination is returned.
Otherwise the status returned is implementation-defined.
C11 §7.22.4.4 5

So better to call as exit(0), exit(EXIT_SUCCESS), exit(EXIT_FAILURE) unless you clearly understand and have some advanced requirements.

Upvotes: 0

usr1234567
usr1234567

Reputation: 23461

Use

exit(1);

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

Documentation at cppreference.com

Upvotes: 9

Giorgi Moniava
Giorgi Moniava

Reputation: 28685

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.

Upvotes: 6

MByD
MByD

Reputation: 137442

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)

Upvotes: 1

chqrlie
chqrlie

Reputation: 145307

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

Upvotes: 2

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