Program termination

Show the syntax for a complete stoppage of a program inside a conditional. This includes all threads/processes which are part of your program.

Explain the cleanup (or lack thereof) caused by the termination (allocated memory, database connections, open files, object finalizers/destructors, run-on-exit hooks, etc.).

Ada

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Ada programs execute in one or more tasks. All tasks created during the execution of a program depend in a hierarchical manner on the task that create them, except for the environment task which executes the "main" procedure for the program. Each task will abort (terminate abnormally) if the task upon which it depends is aborted. This approach to task termination is not recommended because it does not allow tasks to terminate in a known state.

However, this Rosetta Code task requires a simple stoppage of the program including all tasks. The simple way to achieve this is to abort the environment task.

<ada> with Ada.Task_Identification;

procedure Main is

  -- Create as many task objects as your program needs

begin

  -- whatever logic is required in your Main procedure
  if some_condition then
     Ada.Task_Identification.Abort_Task (Ada.Task_Identification.Current_Task);
  end if;

end Main; </ada>

A more correct approach to such termination is to provide an entry in each task created by the environment task which, when called by the task upon which it depends, causes the called task to terminate in a known state.

<ada> procedure Main is

  -- Create as many task objects as your program needs

begin

  -- whatever logic is required in your Main procedure
  if some_condition then
     -- for each task created by the Main procedure
     The_task.Stop;
     -- end the Main procedure
     return;  -- actually, this is not needed
  end if;

end Main; </ada>

BASIC

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Works with: QuickBasic version 4.5

<qbasic>if problem = 1 then

end

end if</qbasic>

C

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<c>#include <stdlib.h>

if(problem){

 exit(integerErrorCode); /*conventionally, error code 0 is the code for "OK", while anything else is an actual problem*/
 /*optionally: return the integerErrorCode from the main() function*/

}</c>

E

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Exit indicating successful completion:

if (true) {
    interp.exitAtTop()
}

Exit indicating some problem:

if (true) {
    interp.exitAtTop("because the task said so")
}

Forth

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debug @
if   QUIT  \ quit back to the interpreter
else BYE   \ exit forth environment completely (e.g. end of a Forth shell script)
then

Fortran

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IF (condition) STOP [message] 
! message is optional and is a character string.
! If present, the message is output to the standard output device.

Haskell

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import Control.Monad
import System.Exit

when problem do
    exitWith ExitSuccess                    (* success *)
    exitWith (ExitFailure integerErrorCode) (* some failure with code *)
    exitFailure                             (* generic failure *)

J

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Given condition, an integer which is zero if everything's OK (and we should NOT exit), or a non-zero exit code if there's a problem (and we should exit), then:

Tacit version:

  2!:55^:] condition

Explicit version:

  3 : 'if. 0~: condition do. 2!:55 condition end.'

Java

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<java>if(problem){

  System.exit(integerErrorCode); //conventionally, error code 0 is the code for "OK", while anything else is an actual problem
  //optionally: Runtime.getRuntime().exit(integerErrorCode);

}</java>

Logo

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Works with: UCB Logo

bye   ; exits to shell

throw "toplevel  ; exits to interactive prompt

pause      ; escapes to interactive prompt for debugging
continue   ; resumes after a PAUSE

OCaml

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<ocaml>if problem then

   exit integerErrorCode (*conventionally, error code 0 is the code for "OK",while anything else is an actual problem*)</ocaml>

Perl

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<perl>if ($problem) {

   exit integerErrorCode; #conventionally, error code 0 is the code for "OK" (you can also omit the argument in this case)
                          #while anything else is an actual problem

}</perl>

Pop11

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if condition then
    sysexit();
endif;

Python

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<python>if problem:

   sys.exit(integerErrorCode) #conventionally, error code 0 is the code for "OK" (you can also omit the argument in this case)
                              #while anything else is an actual problem</python>