C# Byte Array

Byte type

Byte arrays store binary data. This data may be part of a data file, image file, compressed file, downloaded server response, or many other files.

Byte
About part

With byte arrays, we have an ideal representation of this data. The byte array type allows you to store low-level representations. It is useful when optimizing certain methods.


Program icon

This program shows how to allocate a byte array on the managed heap. The program also measures the memory usage of the managed heap before and after this allocation occurs.

Also:The program demonstrates that a byte array is a precise representation of bytes, not a higher-level construct.

Based on:

.NET 4.5

Program that allocates byte array: C#

using System;

class Program
{
    static void Main()
    {
	byte[] array1 = null;
	//
	// Allocate three million bytes and measure memory usage.
	//
	long bytes1 = GC.GetTotalMemory(false);
	array1 = new byte[1000 * 1000 * 3];
	array1[0] = 0;
	long bytes2 = GC.GetTotalMemory(false);
	Console.WriteLine(bytes2 - bytes1);
    }
}

Output

3000032

Garbage collection visualization

Memory usage. The GC.GetTotalMemory method first gathers the memory usage figures from the system before and after the allocation of the byte array.

GC.GetTotalMemory

Then:The byte array variable is assigned a reference to three million bytes in an array allocated on the managed heap.

Array
Three

Allocating a three million element array of bytes causes three million bytes to be added to the memory usage of the program. Byte has minimal overhead.

ValueType
Buffer

Read bytes. We read in a byte array from a file with the System.IO namespace. An easy way to read a file into a binary array is the File.ReadAllBytes method in the File class.

File.ReadAllBytes
Program that uses File.ReadAllBytes: C#

using System;
using System.IO;

class Program
{
    static void Main()
    {
	byte[] array = File.ReadAllBytes("C:\\profiles\\file.bin");
	Console.WriteLine(array[0]);
	Console.WriteLine(array[1]);
	Console.WriteLine(array[2]);
    }
}

Output

56
66
80

Arrow indicates movement

Seek, read. We use Seek() on some Stream classes to read a part of a file into a byte array. It is faster to read in an entire byte array at once. This uses the file system's buffering.

Seek

And:You will find that byte arrays are used in many file input/output programs.


ASPNET web programming framework

ASP.NET makes extensive use of byte arrays in its internal code. You can use the BinaryWrite method and provide a byte array parameter to achieve a fast write to the HTTP response.

Note:Some websites use this approach to optimize server-side performance. Byte arrays are used frequently in this approach.

Response.BinaryWrite
Compression

Modify. It is also possible to modify a byte array. We show how to rewrite a binary file encoded in GZIP to remove parts of the binary format, resulting in superior data compression.

Tip:You can rewrite some byte arrays that contain images or other binary formats and manipulate these kinds of files.

GZIP Header Flag Byte
Array type

Test elements. We can test bytes. With a GZIP file in an array, we can test the first two elements and the length. This tells us if the file contains the correct magic GZIP header bytes.

Note:This process is also called "data sniffing" and is used constantly on the Internet and in web browsers.

GZIP File Test

Download. You can download data over the Internet or other network with a network connection with WebClient. We directly access the bytes of any server's response.

Tip:The data it returns is stored in a byte array. This is useful for scraping web sites or automating tedious Internet tasks.

WebClient
GZIP compression

GZipStream allows you to use a byte array buffer for expanding or compressing GZIP-encoded data. This is an easy way to implement compression or decompression for web applications.

GZipStream
Cache

File system caching. With byte arrays, you are usually just storing the exact data from the file system in the memory of your program.

However:In some cases, this actually duplicates the Windows file system cache mechanism that is optimized for this exact purpose.

Note:Byte array caches on the file system can improve or degrade performance in various situations.


Binary: file containing binary data

BinaryReader. This class allows us to imperatively read in a binary file with more helper methods than testing the bytes yourself.

Class:The BinaryReader class allows you to easily transform individual bytes into integers or strings.

BinaryReader
C# programming language

A summary. We looked at the byte array type, seeing its memory allocation statistics. Next we provided pointers to other articles that focus on the byte array type.


C#: Array