Question

The Microsoft website has the code snippet:

  using (FileStream fsSource = new FileStream(pathSource,
        FileMode.Open, FileAccess.Read))
    {
        // Read the source file into a byte array.
        byte[] bytes = new byte[fsSource.Length];
        int numBytesToRead = (int)fsSource.Length;
        int numBytesRead = 0;
        while (numBytesToRead > 0)
        {
            // Read may return anything from 0 to numBytesToRead.
            int n = fsSource.Read(bytes, numBytesRead, numBytesToRead);

            // Break when the end of the file is reached.
            if (n == 0)
                break;

            numBytesRead += n;
            numBytesToRead -= n;
        }
    }

What concerns me is that fsSource.Length is a long, whereas numBytesRead is an int so at most only 2 * int.MaxValue can be read into bytes (the head and the tail of the stream). So my questions are:

1. Is there some reason that this is OK?
2. If not, how should you read a FileStream into a byte[].

Answer 1

In this situation I wouldn’t even bother processing the FileStream manually; use File.ReadAllBytes instead:

byte[] bytes = File.ReadAllBytes(pathSource);