I have a byte array which contains double values. I want to convert It to double array. Is it possible in C#?
Byte array looks like:
byte[] bytes; //I receive It from socket
double[] doubles;//I want to extract values to here
I created a byte-array in this way (C++):
double *d; //Array of doubles
byte * b = (byte *) d; //Array of bytes which i send over socket
You can't convert an array type; however:
byte[] bytes = ...
double[] values = new double[bytes.Length / 8];
for(int i = 0 ; i < values.Length ; i++)
values[i] = BitConverter.ToDouble(bytes, i * 8);
or (alterntive):
byte[] bytes = ...
double[] values = new double[bytes.Length / 8];
Buffer.BlockCopy(bytes, 0, values, 0, values.Length * 8);
should do. You could also do it in unsafe code:
byte[] bytes = ...
double[] values = new double[bytes.Length / 8];
unsafe
{
fixed(byte* tmp = bytes)
fixed(double* dest = values)
{
double* source = (double*) tmp;
for (int i = 0; i < values.Length; i++)
dest[i] = source[i];
}
}
not sure I recommend that, though
doubleArray[i] = byteArray[i]; does something rather simpler, and will end up with a lot of doubles holding integer values in the range [0-255]I'll add a reference to the super-unsafe code from here C# unsafe value type array to byte array conversions
Be aware that it's based on an undocumented "feature" of C#, so tomorrow it could die.
[StructLayout(LayoutKind.Explicit)]
struct UnionArray
{
[FieldOffset(0)]
public byte[] Bytes;
[FieldOffset(0)]
public double[] Doubles;
}
static void Main(string[] args)
{
// From bytes to floats - works
byte[] bytes = { 0, 1, 2, 4, 8, 16, 32, 64 };
UnionArray arry = new UnionArray { Bytes = bytes };
for (int i = 0; i < arry.Bytes.Length / 8; i++)
Console.WriteLine(arry.Doubles[i]);
}
The only advantage of this method is that it doesn't really "copy" the array, so it's O(1) in space and time over other methods that copy the array that are O(n).
extern, so I can't tell you what the underlying implementation is. I would imagine that it calls down to something like memcpy.