字节顺序：将Java字节转换为C＃

Question

While converting a Java application to C# I came through a strange and very annoying piece of code, which is crucial and works in the original version.

byte[] buf = new byte[length];
byte[] buf2 = bout.toByteArray();
System.arraycopy(buf2, 0, buf, 0, buf2.length);;
for (int i = (int) offset; i < (int) length; ++i) {
  buf[i] = (byte) 255;
}

The part which is causing a casting error is the set into buf[i] of the byte 255: while in Java it works fine, since java.lang.Byte spans from 0 to 255, .NET System.Byte spans from 0 to 254. Because of this limitation, the output in the C# version of the application is that instead of 255, as expected, the buffer contains a set of 254.

Could anyone give me a viable alternative?

Thank you very much for the support.

Answer 1

I think you've misdiagnosed your problem: .NET bytes are 8-bit like everyone else's. A better approach is to try to understand what the Java code is trying to do, then figure out what the cleanest equivalent is in C#.

Answer 2

I think this might be because you're casting the 255 integer literal to a byte, rather than assigning a byte value. I recommend you try using using Byte.MaxValue instead. Byte.MaxValue has a value of 255.

For example:

buf[i] = byte.MaxValue;

Edit: I was wrong; (byte)255 definitely evaluates to 255; I've just confirmed in VS. There must be something you're doing to cause the change elsewhere in your code.

Answer 3

byte.MaxValue equals 255.

The value of this constant is 255 (hexadecimal 0xFF).

Answer 4

Are you absolutely sure about this C# "limitation", according to MSDN : http://msdn.microsoft.com/en-us/library/5bdb6693(VS.71).aspx

The C# byte is an unsigned 8 bit integer with values that can range between 0 and 255.

Answer 5

From MDSN

byte:

The byte keyword denotes an integral type that stores values as indicated in the following table.

• .NET Framework type: System Byte
• Range: byte 0 to 255
• Size : Unsigned 8-bit integer