Getting null terminated string from System.Text.Encoding.Unicode.GetString

If you're sure the rest is all \0, this would work:

cmd = cmd.TrimEnd('\0');

Otherwise, if you just want to get everything before the first null:

int index = cmd.IndexOf('\0');
if (index >= 0)
   cmd = cmd.Remove(index);

Note that Unicode.GetString will take care of double \0s. You should just look for a single \0.

For UTF8/ASCII encodings you can achieve this without reprocessing the string by looking for the first occurrence of the null terminator in the buffer (using System.Array.IndexOf). You can then use the overloaded System.Text.Encoding.Unicode.GetString method to create a string up to the given buffer size.

The example below also caters for a buffer containing no null bytes:

byte[] buffer = new byte[buffSize];
m_dataStream.Read(buffer, 0, buffSize);
var size = System.Array.IndexOf(buffer, (byte)0);
String cmd = System.Text.Encoding.Unicode.GetString(buffer, 0, size < 0 ? buffSize : size);

For UTF16 you could use a similar approach with a for loop (looking for the first pair of null characters ... such as if (buffer[i] == (byte)0 && buffer[i] == buffer[i+1]).

If creating temporary strings is of no concern then the accepted answer is the best solution.

The easiest way would be to trim the string after conversion, as already suggested.

If you know the character count in advance, you could use the GetString overload that takes a start index and a count of bytes, in order to get the correct string, without trimming.

If you do not know the character count in advance, and would like to avoid trimming the string afterwards, you need to trim the byte array first, so you only pass the bytes you are interested in. For Unicode, this would mean removing any bytes after and including the first pair of zeroes.