exit | 易学教程

Better replacement for exit(), atexit() in C

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问题 I am new to C programming. I used to think using exit() was the cleanest way of process termination (as it is capable of removing temporary files, closing open files, normal process termination...), but when I tried man exit command on the terminal (Ubuntu 16.04.5, gcc 5.4.0) I saw the following line: The exit() function uses a global variable that is not protected, so it is not thread-safe. After that I tried to make some research about better replacement for exit() (to change my programming

How to discover that a Scala remote actor is died?

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问题 In Scala, an actor can be notified when another (remote) actor terminates by setting the trapExit flag and invoking the link() method with the second actor as parameter. In this case when the remote actor ends its job by calling exit() the first one is notified by receiving an Exit message. But what happens when the remote actor terminates in a less graceful way (e.g. the VM where it is running crashes)? In other words, how the local actor can discover that the remote one is no longer

collect2: Ld returned 1 exit status build make error

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Compiler: Qt Language: C++ This program is just not for me haha, this is the third time I've had to ask for help, and it's driving me crazy (thank you everyone for being so patient and helpful with me) I tried running my program (again for the millionth time) Since I can't get the ostream sorted out, I commented out all the cout functions in my main so I could deal with the rest of my code. But when I try to run it I get collect2: ld returned 1 exit status in my build issues. I switched to Compile Output... and gosh.. Running build steps for project List... Configuration unchanged, skipping

does exit() free allocated memory on both _SUCCESS and _FAILURE

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问题 This a short snippet of code, with two calls to exit(3) in case of failure. Do these calls deallocate memory allocated by malloc? Google search once says it does, and even more times, it doesn't... Should I add free()? Also: which is better if (!word) (it would also work for eg. word == 0 which is different from word == NULL, so I guess it is wrong) or if (word == NULL) ? char *word = NULL, *temp = NULL; word = (char *)malloc(sizeof(char) * size); if (!word) { /* or maybe rather it should be

'exit' is not a keyword in Python, but no error occurs while using it

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I learn that exit is not a keyword in Python by, import keyword print('exit' in keyword.kwlist) # Output: False But there is no reminder of NameError: name 'exit' is not defined while using it. The output of the following snippet code makes me confused. Can anyone help me out? for i in range(5): print(i) cur=i if i<2 else exit print(cur) # Output 0 1 2 3 4 Use exit() or Ctrl-D (i.e. EOF) to exit I am unable to get related info about exit from Python documentations, except for exit([code=None]) . Keywords are part of the python syntax. They usually have special meaning in statements (e.g. for ,

PHP - exit from IF block

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问题 How can I exit a if block if a certain condition is met? I tried using break but it doesn't work: if($bla): $bla = get_bla(); if(empty($bla)) break; do($bla); endif; it says: Fatal error: Cannot break/continue 1 level in... 回答1: Why not just turn it around. if($bla): $bla = get_bla(); if(!empty($bla)) { do($bla); } endif; That way it will only run your code if $bla isn't empty.. That's kinda the point with if-statements 回答2: In PHP 5.3 you can use goto if($bla): $bla = get_bla(); if(empty(

Diagnosing an app that fails to halt

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Our Windows app is often hanging in memory and I'm trying to use windbg to track down the problem. I'm very new to windbg and could use some advice (I have started to read Advanced Windows Debugging though). The app is a mix of C++ and COM objects written in VB. Occasionally when you exit, the app appears to go away but task manager shows it hanging around in memory, apparently idle. !threads shows me this: ThreadCount: 2 UnstartedThread: 0 BackgroundThread: 2 PendingThread: 0 DeadThread: 0 Hosted Runtime: no PreEmptive GC Alloc Lock ID OSID ThreadOBJ State GC Context Domain Count APT

Execute batch code when user click on exit

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问题 I am working on some code testing, and I stumbled on a problem I can't find or fix. My problem is: If a user accidentally closes the cmd window, I'd like to execute a batch code before it actually closes. For example: I run script A.bat . When a user wants to exit, I want it to delete my B.bat and then close the window. This is how the code may look like: @ECHO OFF echo Welcome to A.bat del B.bat (when user exits the window) I couldn't find it on google and forums, so I thought maybe you guys

Efficient exit from multithreaded application (specifics)

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I've read a few sources on proper methods of bubbling a message out from a thread to all other threads to exit gracefully (every thread performs it's own exit routine). Of these, I liked the idea of a global atomic boolean that can be flagged from any thread, and all other threads check this flag to perform an exit routine - when all threads are joined, the main thread can then exit the application. Purely computation threads would probably be handled differently, right? Is this efficient and safe? Is there a better way to do this? Thanks! Roddy In Windows, I use QueueUserAPC to call a

Exit from a stored procedure

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I have some loop and a condition. If codition is matched then I want to stop or exit from the stored procedure. How to do that? while @@fetch_status=0 begin if x=0 'exit stored procedure end if you are using Microsoft Sql Server than you can use Return Statement while @@fetch_status=0 begin if x=0 return; end By @@fetch_status it looks like your inside a cursor loop so I would not return at that point as you will skip tidying up after yourself. ... if x=0 GOTO DONE ... /* at the end of the sp */ DONE: CLOSE @your_cur DEALLOCATE @your_cur try use return while @@fetch_status=0 begin if x=0