MemoryStream: why convert to byte after readByte

问题

In this example from MS, you'll notice that after we read a byte from memory stream, it goes into an int which must then be converted to byte. It stikes me as strange that a function like .ReadByte() doesn't return a byte in the first place. Is there a reason why MS did it this way?

// Read the remaining bytes, byte by byte.
while(count < memStream.Length)
{
    byteArray[count++] =
        Convert.ToByte(memStream.ReadByte());
}

a thought occured to me. Perhaps this comes down to usage. Perhaps ReadByte() is often used to retrieve short lengths, which subsequents get consumed in the retrieve via length variety

int length=ms.ReadByte();
ms.Read(buf,0,lenth);

i.e. you can use the length without a cast. Is this a good enough reason?

回答1:

This is not specific to Memory stream, rather it is because of the design of base class "Stream" and the reason for that is

Return value:

The unsigned byte cast to an Int32, or -1 if at the end of the stream.

-1 cannot be represented using unsigned byte

回答2:

When you use ReadByte If the read is successful then the current position within the stream is advanced by one byte. but its designed to return -1 if the end of the stream has been reached.

Now this would not be a valid value for Byte (its unsigned)

ms.Read(buf,0,lenth); here lenth is the number of bytes to read from the stream and what you get from ReadByte is first byte its not be used in the this fashion, something like

byte[] buff = new byte[ms.Length];
ms.Read(buff , 0, buff .Length);

回答3:

I do believe they are converting with that from int to byte in a reallllllly nice way, since ReadByte() returns an int and their byteArray is of type int[].

来源：https://stackoverflow.com/questions/6868809/memorystream-why-convert-to-byte-after-readbyte

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