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C# BinaryWriter TypeUse the BinaryWriter class to write an output file containing integers.
BinaryWriter. This C# type creates binary files. A binary file uses a specific data layout for its bytes. The BinaryWriter type is ideal for creating these files.
BinaryReader
File
Type info. BinaryWriter is a stream-based mechanism for writing data to a file location on the disk. Here we see an example of using the BinaryWriter class, which will create the binary file.
An example. BinaryWriter writes data. It writes primitive types like int, uint or char. In this example, File.Open returns a stream that the BinaryWriter writes through to.
Int, uint
Char
Next We call Write to write a value to the file. The Write method is overloaded, which means it handles the exact type you pass it correctly.
File.Open
Overload
C# program that uses BinaryWriter
using System.IO; class Program { static void Main() { W(); } static void W() { // Create 12 integers. int[] a = new int[] { 1, 4, 6, 7, 11, 55, 777, 23, 266, 44, 82, 93 }; // Use using statement and File.Open. using (BinaryWriter b = new BinaryWriter(File.Open("file.bin", FileMode.Create))) { // Use foreach and write all 12 integers. foreach (int i in a) { b.Write(i); } } } }
Close. The using statement will cause the Dispose method to be called. In the Dispose implementation, Close is called—an explicit Close call is not necessary.
Using
Also If you call BinaryWriter's virtual Close implementation, it calls Dispose. And Dispose then calls the Stream's Close implementation.
Stream
Implementation of Dispose, IL:
.method family hidebysig newslot virtual instance void Dispose(bool disposing) cil managed { // Code size 15 (0xf) .maxstack 8 IL_0000: ldarg.1 IL_0001: brfalse.s IL_000e IL_0003: ldarg.0 IL_0004: ldfld class System.IO.Stream System.IO.BinaryWriter::OutStream IL_0009: callvirt instance void System.IO.Stream::Close() IL_000e: ret } // end of method BinaryWriter::Dispose
File data. What does the output file look like visually when you inspect it in an editor such as Visual Studio? It is not something easily read—it looks like random bytes.
And This is because the data is not encoded as a text file but instead a more efficient, machine-level representation of numeric data.
Tip Don't worry—the file can still be treated as a series of numbers. Buy we must use a program to read it.
Summary. BinaryWriter is an easy way to create a binary file. Ideal for certain file formats that your programs must support, the BinaryWriter is used in many projects around the world.
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