writer | 易学教程

Write one single bit to binary file using BinaryWriter

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I want to write one single bit to a binary file. using (FileStream fileStream = new FileStream(@"myfile.bin", FileMode.Create)) using (BinaryWriter binaryWriter = new BinaryWriter(fileStream)) { binaryWriter.Write((bool)10); } Something like binaryWriter.Write((bit)1); When I use binaryWriter.Write((bool)1) the file has one byte, but I want to write one single bit. Is this possible? You cannot store only 1 bit in a file. Almost all modern filesystems and hardware store data in segments of 8 bits, aka bytes or octets. If you want store a bit value in a file, store either 1 or 0 as a byte

Does Writer Monad guarantee right associative concatenation?

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It was claimed in Validations in Haskell that use of a Writer guarantees right-associative concatenation. However, this example seems to show otherwise. What's the correct answer? {-# LANGUAGE OverloadedStrings #-} import Control.Monad.Writer import Data.String data TM = TMempty | TMappend TM TM | TMfromString String instance IsString TM where fromString = TMfromString instance Monoid TM where mempty = TMempty mappend = TMappend instance Show TM where showsPrec d TMempty = showString "\"\"" showsPrec d (TMfromString s) = showString $ show s showsPrec d (TMappend a b) = showParen (d > 0) $

Does Python csv writer always use DOS end-of-line characters?

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I realize that the csv library in Python always generates DOS end-of-line characters. Even if I use the 'wb' mode, even if I use Linux. import csv f = open('output.txt', 'wb'); writer = csv.writer(f) writer.writerow([2,3,4]); f.close() The above code always uses '\r\n' as the end of line separator. How can I make it use use '\n' only? You can give your writer instance a custom lineterminator argument in the constructor: writer = csv.writer(f, lineterminator="\n") Don Kirkby As Niklas answered , the lineterminator argument lets you choose your line endings. Rather than hard coding it to \n ,

Write and read from a fifo from two different script

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问题 I have two bash script. One script write in a fifo. The second one read from the fifo, but AFTER the first one end to write. But something does not work. I do not understand where the problem is. Here the code. The first script is (the writer): #!/bin/bash fifo_name="myfifo"; # Se non esiste, crea la fifo; [ -p $fifo_name ] || mkfifo $fifo_name; exec 3<> $fifo_name; echo "foo" > $fifo_name; echo "bar" > $fifo_name; The second script is (the reader): #!/bin/bash fifo_name="myfifo"; while true

Writing per line new CSV File (JAVA)

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问题 I have the following code: public static void main(String[] args) throws IOException { //File being read: String fileName = "src/data/Belgium.csv"; String[] nextLine; try (CSVReader reader = new CSVReader(new FileReader(fileName), ',', '"', 1)) { while ((nextLine = reader.readNext()) != null) { for (String line : nextLine) { //NewFile //When 2nd parameter - ture, it gets so big, that excel can't handle it anymore... FileWriter writer = new FileWriter("src/dataNew/BelgiumNew1.csv", true); line

Reader/Writer与InputStream/OutputStream的区别

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1. Readers and writers are like input streams and output streams. The primary difference lies in the fundamental datatype that is read or written; streams are byte-oriented, whereas readers and writers use characters and strings. 2. The reason for this is internationalization. Readers and writers were designed to allow programs to use a localized character set and still have a stream-like model for communicating with external devices. 3. These are analogous to the read( ) methods defined for InputStream. For example, read( ) still returns an integer. The difference is that, instead of data

When to use which Writer subclass in Java; common practices

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问题 I have always been slightly confused with the amount of different IO implementations in Java, and now that I am completely stuck in my project development, I was taking my time to read up on useful stuff meanwhile. I have realized that there is no newbie-friendly comparison (apart from short explanation at API for Writer class) between the different subclasses of the Writer class. So I figured I'd fire away the question, what are those different subclasses good for? For example, I usually use

What is the difference between append and write methods of java.io.writer?

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问题 The java.io.Writer interface has two methods called append and write. What are the differences between these two? It even says that An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation out.write(c) so what is the reason for having two method name variants? 回答1: There are minor differences between append() and write(). All of which you can work out by reading the Javadocs. Hint. ;) write will only take a String which must not be null and

Golang function pointer as a part of a struct

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问题 I have the following code: type FWriter struct { WriteF func(p []byte) (n int,err error) } func (self *FWriter) Write(p []byte) (n int, err error) { return self.WriteF(p) } func MyWriteFunction(p []byte) (n int, err error) { // this function implements the Writer interface but is not named "Write" fmt.Print("%v",p) return len(p),nil } MyFWriter := new(FWriter) MyFWriter.WriteF = MyWriteFunction // I want to use MyWriteFunction with io.Copy io.Copy(MyFWriter,os.Stdin) What I am trying to do is

What is the difference between append and write methods of java.io.writer?

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The java.io.Writer interface has two methods called append and write. What are the differences between these two? It even says that An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation out.write(c) so what is the reason for having two method name variants? There are minor differences between append() and write(). All of which you can work out by reading the Javadocs. Hint. ;) write will only take a String which must not be null and returns void append will take any CharSequence which can be null and return the Writer so it can be chained.