Question

How do I convert a double[] array to a byte[] array and vice versa?

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine(sizeof(double));
        Console.WriteLine(double.MaxValue);

        double[] array = new double[] { 10.0, 20.0, 30.0, 40.0 };
        byte[] convertedarray = ?

        Console.Read();
    }
}

Answer 1

Assuming you want the doubles placed in the corresponding byte array one after the other, LINQ can make short work out of this:

static byte[] GetBytes(double[] values)
{
    return values.SelectMany(value => BitConverter.GetBytes(value)).ToArray();
}

Alternatively, you could use Buffer.BlockCopy():

static byte[] GetBytesAlt(double[] values)
{
    var result = new byte[values.Length * sizeof(double)];
    Buffer.BlockCopy(values, 0, result, 0, result.Length);
    return result;
}

To convert back:

static double[] GetDoubles(byte[] bytes)
{
    return Enumerable.Range(0, bytes.Length / sizeof(double))
        .Select(offset => BitConverter.ToDouble(bytes, offset * sizeof(double)))
        .ToArray();
}

static double[] GetDoublesAlt(byte[] bytes)
{
    var result = new double[bytes.Length / sizeof(double)];
    Buffer.BlockCopy(bytes, 0, result, 0, bytes.Length);
    return result;
}