C# 3.0 Cookbook, 3rd Edition

2.11. Passing a String to a Method That Accepts Only a Byte[]

Problem

Many methods in the FCL accept a byte[] consisting of characters instead of a string. Some of these methods include:

	System.Diagnostics.EventLog.WriteEntry
	System.IO.BinaryWriter.Write
	System.IO.FileStream.Write
	System.IO.FileStream.BeginWrite
	System.IO.MemoryStream.Write
	System.IO.MemoryStream.BeginWrite
	System.Net.Sockets.Socket.Send
	System.Net.Sockets.Socket.SendTo
	System.Net.Sockets.Socket.BeginSend
	System.Net.Sockets.Socket.BeginSendTo
	System.Net.Sockets.NetworkStream.Write
	System.Net.Sockets.NetworkStream.BeginWrite
	System.Security.Cryptography.CryptoStream.Write
	System.Security.Cryptography.CryptoStream.BeginWrite

In many cases, you might have a string that you need to pass into one of these methods or some other method that accepts only a byte[]. You need a way to break up this string into a byte[].

Solution

To convert a string to a byte[] of ASCII values, use the GetBytes method on the Encoding class:

	byte[] retArray = Encoding.ASCII.GetBytes(characters);

To convert a string to a byte[] of Unicode values, use the GetBytes method on the Encoding class:

	byte[] retArray = Encoding.Unicode.GetBytes(characters);

Discussion

The GetBytes method of the Encoding class (returned by the ASCII property) converts ASCII characters—contained in either a char[] or a string—into a byte[] of 7-bit ASCII values. Any value larger than 127 (0x7F) is converted to the ? character. The Encoding class can be found in the System.Text ...