flush | 易学教程

Flushing stdin after every input - which approach is not buggy?

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问题 After Mark Lakata pointed out that the garbage isn't properly defined in my question I came up with this. I'll keep this updated to avoid confusions. I am trying to get a function that I can call before a prompt for user input like printf("Enter your choice:); followed a scanf and be sure that only the things entered after the prompt would be scanned in by scanf as valid input. As far as I can understand the function that is needed is something that flushes standard input completely. That is

Does python logging flush every log?

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问题 When I write a log to file using the standard module logging , will each log be flushed to disk separately? For example, will the following code flush log by 10 times? logging.basicConfig(level=logging.DEBUG, filename='debug.log') for i in xrange(10): logging.debug("test") if so, will it slow down ? 回答1: Yes, it does flush the output at every call. You can see this in the source code for the StreamHandler : def flush(self): """ Flushes the stream. """ self.acquire() try: if self.stream and

Force flushing of output to a file while bash script is still running

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I have a small script, which is called daily by crontab using the following command: /homedir/MyScript &> some_log.log The problem with this method is that some_log.log is only created after MyScript finishes. I would like to flush the output of the program into the file while it's running so I could do things like tail -f some_log.log and keep track of the progress, etc. bash itself will never actually write any output to your log file. Instead, the commands it invokes as part of the script will each individually write output and flush whenever they feel like it. So your question is really

What does flushing the buffer mean?

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I am learning C++ and I found something that I can't understand: Output buffers can be explicitly flushed to force the buffer to be written. By default, reading cin flushes cout ; cout is also flushed when the program ends normally. So flushing the buffer (for example an output buffer): does this clear the buffer by deleting everything in it or does it clear the buffer by outputting everything in it? Or does flushing the buffer mean something completely different? David Heffernan Consider writing to a file. This is an expensive operation. If in your code you write one byte at a time, then each

Does reading from stdin flush stdout?

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stdout is line-buffered when connected to a terminal, but I remember reading somewhere that reading (at least from stdin) will automatically flush stdout. All C implementations that I have used have done this, but I can't find it in the standard now. It does make sense that it works that way, otherwise code like this: printf("Type some input: "); fgets(line, sizeof line, stdin); would need an extra fflush(stdout); So is stdout guaranteed to be flushed here? EDIT: As several replies have said, there seems to be no guarantee in the standard that the output to stdout in my example will appear

PHP Flush() not working in Chrome

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问题 I stumbled upon this function which promised to work across IE, FF & Chrome. But it does not work in Chrome. Is there a work around? function buffer_flush(){ echo str_pad('', 512); echo ''; if(ob_get_length()){ @ob_flush(); @flush(); @ob_end_flush(); } @ob_start(); } 回答1: Here's how I got flush() working in a while loop in Chrome 12.0.742.122 with PHP 5.3.6: echo("<html><body>"); while(1) { echo(str_pad($my_string_var,2048," ")); @ob_flush(); flush(); } Using a lesser str_pad value

Python3 sleep() problem

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问题 I was writing a simple program on Python 3.1 and I stumbled upon this: If I run this on the IDLE it works as intended - prints "Initializing." and then adds two dots, one after each second, and waits for input. from time import sleep def initialize(): print('Initializing.', end='') sleep(1) print(" .", end='') sleep(1) print(" .", end='') input() initialize() The problem is that when I double-click the .py to execute the file, it runs on python.exe instead of pythonw.exe, and strange things

endl and flushing the buffer

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In the C++ primer book, in chapter (1), it mentions the following: endl is a special value, called a manipulator, that when written to an output stream has the effect of writing a newline to the output and ﬂushing the buffer associated with that device . By ﬂushing the buffer, we ensure that the user will see the output written to the stream immediately. What is meant by "flushing the buffer" here? Output is generally buffered before it's written to the intended device. That way, when writing to slow to access devices(like files), it doesn't have to access the device after every single

How to empty/flush Windows READ disk cache in C#?

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问题 If I am trying to determine the read speed of a drive, I can code a routine to write files to a filesystem and then read those files back. Unfortunately, this doesn't give an accurate read speed because Windows does disk read caching. Is there a way to flush the disk read cache of a drive in C# / .Net (or perhaps with Win32 API calls) so that I can read the files directly from the drive without them being cached? 回答1: Why DIY? If you only need to determine drive speed and not really

When Hibernate flushes a Session, how does it decide which objects in the session are dirty?

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问题 My understanding of Hibernate is that as objects are loaded from the DB they are added to the Session. At various points, depending on your configuration, the session is flushed. At this point, modified objects are written to the database. How does Hibernate decide which objects are 'dirty' and need to be written? Do the proxies generated by Hibernate intercept assignments to fields, and add the object to a dirty list in the Session? Or does Hibernate look at each object in the Session and