VB.NET Byte Array: Memory UsageUse Byte arrays to store data. BinaryReader and ReadByte can be used with a byte array.
Byte arrays hold data in an efficient way. Any file can be read in, or downloaded, into a Byte array. Often this is much more efficient than other representations.ByteArray
Notes, handling. Data in a Byte array is sometimes harder to manipulate and read. Often strings or string arrays are a better storage format.
We measure byte array memory use. We allocate a Byte array. The reference to the Byte array requires 4 or 8 bytes on the stack.
And: The 3 million elements, bytes, of the array require a bit less than 3 megabytes of memory.
Important: In an array, each byte element requires exactly 1 byte. But there are additional costs involved.
Program: This example uses a Byte array but not in a useful way. Byte arrays are useful as storage regions for images or binary data.
VB.NET program that creates Byte array
Dim value1 As Long = GC.GetTotalMemory(False)
' Create an array of 3 million bytes.
' ... We specify the last index to create an array.
Dim bytes(1000 * 1000 * 3 - 1) As Byte
bytes(0) = 0
' Get memory and print the change.
Dim value2 As Long = GC.GetTotalMemory(False)
Console.WriteLine(value2 - value1)
' Ensure we have exactly 3 million bytes.
The BinaryReader and BinaryWriter types are often used with Byte arrays. It is possible to use a Byte array, wrapped in a MemoryStream, with these types as a backing store.
Info: This is an efficient approach to reading bytes, as it does not access the hard disk more than once.BinaryReader
Here: We use the File.ReadAllBytes Function. Then we wrap the Byte array in a MemoryStream.
And: We pass that MemoryStream to a BinaryReader. We can use the Byte array, which stores a JPG image now, in the same way as a file.File
VB.NET program that uses Byte array
' Byte array stores a JPG.
Dim array() As Byte = File.ReadAllBytes("C:\athlete.jpg")
Using memory As MemoryStream = New MemoryStream(array)
Using reader As BinaryReader = New BinaryReader(memory)
' Display values of first two bytes of JPG in memory.
To create an array of 3 million elements, we must specify the last required element index, which is 3 million minus one. This is a key difference between VB.NET and C#.
Note: Thanks to David Deley for pointing out an error in a previous version of the byte array program.
A summary. A Byte array is a versatile type. It stores a direct, accurate representation of binary data. This includes images (JPG, PNG) as well as many different file formats.
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