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En C#, BinaryWriter est une classe utilisée pour écrire des types primitifs sous forme de données binaires dans un flux de codage particulier. Il est présent sous l'espace de noms System.IO.
Voici quelques points importants concernant BinaryWriter :
Le constructeur pour créer un objet de BinaryWriter est disponible sous quatre formes surchargées. La syntaxe pour créer un objet BinaryWriter en utilisant tous ses constructeurs surchargés est la suivante :
Syntaxe n°1
protected BinaryWriter();
Il est utilisé pour initialiser une instance de la classe BinaryWriter.
Syntaxe #2
BinaryWriter binaryWriter = new BinaryWriter(outputStream) ;
L'instruction ci-dessus initialise une nouvelle instance de la classe BinaryWriter sur la base du flux spécifié (outputStream) et en utilisant le codage de caractères UTF-8.
Syntaxe #3
BinaryWriter binaryWriter = new BinaryWriter(outputStream, encoding);
L'instruction ci-dessus initialise une nouvelle instance de BinaryWriter en fonction du flux spécifié (outputStream) et du codage de caractères (encoding).
Syntaxe #4
BinaryWriter binaryWriter = new BinaryWriter(outputStream, encoding, true);
Code :
using (BinaryWriter binaryWriter = new BinaryWriter(File.Open(fileName, FileMode.Create )) ) { //user code }
Ici, la méthode File.Open() renvoie l'objet FileStream qui permet de créer une instance de BinaryWriter.
Le tableau suivant montre les détails de certaines méthodes Write() de BinaryWriter pour différents types de données :
Method | Description |
Write(Boolean) | This method is used to write the one-byte Boolean value to the present stream; 0 represents false while 1 represents true. |
Write(Byte) | This method is used to write an unsigned byte to the present stream and then it advances the position of the stream by one byte. |
Write(Char) | This method is used to write Unicode character to present stream and also it advances the present stream position according to the character encoding used and according to the characters being written to the present stream. |
Write(Decimal) | This method is used to write a decimal value to the present stream and also it advances the position of the current stream by sixteen bytes. |
Write(Double) | This method is used to write an eight-byte floating-point value to the present stream and then it also advances the position of the current stream by eight bytes. |
Write(Int32) | This method is used to write a four-byte signed integer to the present stream and then it advances the position of current stream by four bytes. |
Write(String) | This method is used to write length prefixed string to present stream in the present encoding of BinaryWriter and also it advances the current stream position according to the encoding used and according to the characters being written to the present stream. |
Example showing the creation of file:
Code:
using System; using System.IO; namespace ConsoleApp4 { public class Demo { string fileLocation = "E:\\Content\\newBinaryFile.dat"; public void WritingFile() { try { //checking if file exists if (File.Exists(fileLocation)) { File.Delete(fileLocation); } FileStream fileStream = new FileStream(fileLocation, FileMode.Create, FileAccess.Write, FileShare.ReadWrite); //creating binary file using BinaryWriter using (BinaryWriter binaryWriter = new BinaryWriter(fileStream)) { //writing data using different Write() methods //of BinaryWriter binaryWriter.Write(5253); binaryWriter.Write("This is a string value."); binaryWriter.Write('A'); } } catch (Exception exception) { Console.WriteLine(exception.Message); } } public void ReadingFile() { try { FileStream fileStream = new FileStream(fileLocation, FileMode.Open, FileAccess.Read, FileShare.ReadWrite); using (BinaryReader binaryReader = new BinaryReader(fileStream)) { Console.WriteLine("IntegerValue = " + binaryReader.ReadInt32()); Console.WriteLine("StringValue = " + binaryReader.ReadString()); Console.WriteLine("CharValue = " + binaryReader.ReadChar()); } } catch (Exception exception) { Console.WriteLine(exception.Message); } } } public class BinaryWriterDemo { static void Main(string[] args) { Demo demoObj = new Demo(); demoObj.WritingFile(); demoObj.ReadingFile(); Console.ReadLine(); } } }
Output:
In C#, the BinaryWriter class is used to write primitive types as binary information to the stream. If the encoding is not defined, then the BinaryWriter class uses the default UTF-8 character encoding to write data to a binary file. An object of BinaryWriter can be created using the Stream object.
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