Creating a byte array from a stream

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Creating a byte array from a stream

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It really depends on whether or not you can trust `s.Length`. For many streams, you just don't know how much data there will be. In such cases - and before .NET 4 - I'd use code like this:

```
public static byte[] ReadFully(Stream input)
{
byte[] buffer = new byte[16*1024];
using (MemoryStream ms = new MemoryStream())
{
int read;
while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
{
ms.Write(buffer, 0, read);
}
return ms.ToArray();
}
}

```

With .NET 4 and above, I'd use [`Stream.CopyTo`](https://msdn.microsoft.com/en-us/library/system.io.stream.copyto), which is basically equivalent to the loop in my code - create the `MemoryStream`, call `stream.CopyTo(ms)` and then return `ms.ToArray()`. Job done.

I should perhaps explain why my answer is longer than the others. [`Stream.Read`](http://msdn.microsoft.com/en-us/library/system.io.stream.read.aspx) doesn't guarantee that it will read everything it's asked for. If you're reading from a network stream, for example, it may read one packet's worth and then return, even if there will be more data soon. [`BinaryReader.Read`](http://msdn.microsoft.com/en-us/library/system.io.binaryreader.read.aspx) will keep going until the end of the stream or your specified size, but you still have to know the size to start with.

The above method will keep reading (and copying into a `MemoryStream`) until it runs out of data. It then asks the `MemoryStream` to return a copy of the data in an array. If you know the size to start with - or *think* you know the size, without being sure - you can construct the `MemoryStream` to be that size to start with. Likewise you can put a check at the end, and if the length of the stream is the same size as the buffer (returned by [`MemoryStream.GetBuffer`](http://msdn.microsoft.com/en-us/library/system.io.memorystream.getbuffer.aspx)) then you can just return the buffer. So the above code isn't quite optimised, but will at le

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