C# - Cast a byte array to an array of struct and vice-versa (reverse)

Question

I would like to save a Color[] to a file. To do so, I found that saving a byte array to a file using \"System.IO.File.WriteAllBytes\" should be very efficient.

I wou

Answer 1

You could use pointers if you really want to copy each byte and not have a copy but the same object, similar to this:

var structPtr = (byte*)&yourStruct;
var size = sizeof(YourType);
var memory = new byte[size];
fixed(byte* memoryPtr = memory)
{
    for(int i = 0; i < size; i++)
    {
        *(memoryPtr + i) = *structPtr++;
    }
}
File.WriteAllBytes(path, memory);

I just tested this and after adding the fixed block and some minor corrections it looks like it is working correctly.

This is what I used to test it:

public static void Main(string[] args)
{
    var a = new s { i = 1, j = 2 };
    var sPtr = (byte*)&a;
    var size = sizeof(s);
    var mem = new byte[size];
    fixed (byte* memPtr = mem)
    {
        for (int i = 0; i < size; i++)
        {
            *(memPtr + i) = *sPtr++;
        }
    }
    File.WriteAllBytes("A:\\file.txt", mem);
}

struct s
{
    internal int i;

    internal int j;
}

The result is the following:

(I manually resolved the hex bytes in the second line, only the first line was produced by the program)