BinaryWriter is a class in the .NET Framework that provides methods for writing binary data to a stream. It is used to write data in a specific binary format, such as when serializing data or writing to a binary file. The BinaryWriter class is part of the System.IO namespace in .NET.
To use BinaryWriter, you need to first create an instance of the class and pass a stream to its constructor. Once you have a BinaryWriter object, you can use its methods to write different types of data to the stream.
Here is an example of using BinaryWriter to write some data to a file:
using System; using System.IO; class Program { static void Main(string[] args) { // Create a FileStream to write to a file using (FileStream stream = new FileStream("data.bin", FileMode.Create)) { // Create a BinaryWriter to write binary data to the stream using (BinaryWriter writer = new BinaryWriter(stream)) { // Write some data to the file writer.Write("Hello, world!"); writer.Write(42); writer.Write(true); } } } }
In this example, we create a FileStream object to write to a file named "data.bin". We then create a BinaryWriter object using the FileStream object as its argument. The Write method of the BinaryWriter object is then used to write a string, an integer, and a boolean value to the stream in binary format.
When the code is executed, it will create a binary file named "data.bin" in the same directory as the program. If we open this file with a hex editor, we can see that the data is stored in binary format:
Code 48 65 6C 6C 6F 2C 20 77 6F 72 6C 64 21 2A 00 00
01 2A 01
In this example, the string "Hello, world!" is stored as a sequence of bytes representing the ASCII values of each character. The integer value 42 is stored in little-endian format as two bytes (2A 00), and the boolean value true is stored as a single byte (01).
In addition to the Write method, the BinaryWriter class also provides methods for writing other data types to the stream, such as floats, doubles, and decimal values. The class also provides methods for writing variable-length data, such as strings and arrays, in a compact binary format.
It is important to note that when using BinaryWriter to write data in binary format, the same format must be used when reading the data back from the stream using a BinaryReader or similar class. If the data is not read back in the same format, it may not be interpreted correctly.
