exit

I am learning C and as an exercise, I'm trying to write a simple program without any semicolons. I've had some trouble with replacing return 0 statement but I've found that this is (the only?) way to do it in C: if(exit(0),0){} . How exactly does this statement work? I know that exit() from stdlib is a void function but I don't understand what the ,0 part in the if works (the rest is clear to me). The , operator in C evaluates both its arguments, and returns the value of the second one. So the expression exit(0), 0 calls exit(0) and returns 0. So the code you posted is effectively equivalent

Microsoft BASIC , GW-BASIC and BASICA all use a prompt that looks like this: I can't figure out how to exit any of these. Typing END does not exit them. EXIT , QUIT , Q , Ctrl+C , and everything else that I can think of also does not work. I'm sure there's a way to do this. I can't imagine everyone who used BASICA on DOS had to restart their machine every single time they wanted to exit the development environment. So, how do I exit from the old BASIC editor prompt? Jeff Zeitlin GWBASIC and its clones (e.g., IBM's BASIC and BASICA) exited to the DOS prompt with the command system . Although

I have a console-based QCoreApplication which has timers and does socket communication and also uses locked mutex. When I close the application manually, it gives error saying some mutex is locked and it is timed out. Is there any way I can do clean up in a console application when user closes it? Cleanup should be handled by destructors and child-parent relationship. Make your master object (the one in the main) a child of QApplication so it is destructed with all its childs before QApplication is. Are you sure you killed all your threads? If it is a thread with an eventloop be sure to call

I know that in WP7 it is not possible to exit application programatically. So haw can I handle the following need? My MainPage is empty, and has has the only purpose to make a test: if user never filled a preference page, redirects to Page_B.xaml (a page which collects his preferences, such as language aond other info which are needed in order to run the app). Otherwise redirect to Page_A.xaml. So the first page that user is shown is either Page_A or Page_B (depending if this is the first time he/she runs the app). HERE IS THE PROBLEM: when user select the hardware "Back" button while in Page

I have seen some code do this: if(something){ echo 'exit from program'; die; } ...more code And others that just use die : if(something) die('exit from program'); ...more code Is there any inherent difference in when it would end the program, should I be aware of the code that comes after it? etcetera UPDATE I am asking mainly, if it is a coding style, or if there is a real reason why some is coded one way versus another. I am not asking what the difference between exit and die is. No, there is no difference; they will both write "exit" to STDOUT and terminate the program. I would prefer the

I have a little frame where I ask user & password. This frame will be opened clicking over a button in a main window. Then I have two buttons: ok and cancel. When I click on "cancel" button, I need to close this frame without exiting the app. How can I do that? You can use either Frame.hide() or Frame.dispose(). I would also recommend to look into JDialog or JOptionPane Correction: hide() is deprecated. SetVisible(false) should be used instead Maybe a cleaner way is just change the setDefaultCloseOperation from EXIT_ON_CLOSE to DISPOSE_ON_CLOSE : setDefaultCloseOperation(JFrame.DISPOSE_ON

一、上下文管理协议其实就是 with obje as f 在文件操作时用过，with open("a.txt","r") as f: 当时的好处就是不用手动关闭文件了 学到现在我们知道了，其实open也是一个类，之所以能用 with as 是类里做了“小手脚” class Foo: def __init__(self,name): self.name = name def __enter__(self): print("执行enter") return self def __exit__(self, exc_type, exc_val, exc_tb): print("执行exit") with Foo('a.txt') as f: print(f) print(f.name) print("======>") print("======>") print("000000000000000") 上述过程： 1. with obj ------->触发 obj.__enter__(), 拿到的返回值赋值给 f (with obj as f 等同于 f= obj.__enter__()) 2. with obj as f 内的代码执行完毕后触发 __exit__() 二、__exit__中的异常处理 先了解下异常 分为：异常类，异常值，追踪信息 ①没有异常的情况下