You can get hold of the file descriptor for standard out through FileDescriptor.out. To reset standard out to print to console, you do System.setOut(new PrintStream(new FileOutputStream(FileDescriptor.out))); Another way is to simply hold on to the original object, as follows: PrintStream stdout = System.out; System.setOut(new PrintStream(logFile)); // … System.setOut(stdout); // reset to standard output
If you want to get new line characters used in current OS like \r\n for Windows, you can get them by System.getProperty(“line.separator”); since Java7 System.lineSeparator() or as mentioned by Stewart generate them via String.format(“%n”); You can also use PrintStream and its println method which will add OS dependent line separator at the end of your … Read more
BufferedOutputStream helps when the writes are smaller than the buffer size e.g. 8 KB. For larger writes it doesn’t help nor does it make it much worse. If ALL your writes are larger than the buffer size or you always flush() after every write, I would not use a buffer. However if a good portion … Read more
You could define a recursive function that prints “a string” n times (n being the parameter of the function), like this: printStringNTimes 0 = return () printStringNTimes n = do putStrLn “a string” printStringNTimes (n-1) main = printStringNTimes 10 A somewhat more general approach would be to define a function that repeats any IO action … Read more
The BufferedWriter will already flush when it fills its buffer. From the docs of BufferedWriter.write: Ordinarily this method stores characters from the given array into this stream’s buffer, flushing the buffer to the underlying stream as needed. (Emphasis mine.) The point of BufferedWriter is basically to consolidate lots of little writes into far fewer big … Read more
Using ElementTree: import xml.etree.ElementTree # Open original file et = xml.etree.ElementTree.parse(‘file.xml’) # Append new tag: <a x=’1′ y=’abc’>body text</a> new_tag = xml.etree.ElementTree.SubElement(et.getroot(), ‘a’) new_tag.text=”body text” new_tag.attrib[‘x’] = ‘1’ # must be str; cannot be an int new_tag.attrib[‘y’] = ‘abc’ # Write back to file #et.write(‘file.xml’) et.write(‘file_new.xml’) note: output written to file_new.xml for you to experiment, … Read more
I think the best explanation I’ve heard was actually fairly recently on SO. IO Foo is a recipe for creating a Foo. Another common, more literal, way of saying this is that it is a “program that produces a Foo“. It can be executed (many times) to create a Foo or die trying. The execution … Read more
There’s no such specifier. I think what you’re doing (casting the pid_t to long and printing it with “%ld”) is fine; you could use an even wider int type, but there’s no implementation where pid_t is bigger than long and probably never will be.
Before the IO monad was introduced, main was a function of type [Response] -> [Request]. A Request would represent an I/O action like writing to a channel or a file, or reading input, or reading environment variables etc.. A Response would be the result of such an action. For example if you performed a ReadChan … Read more