MemCpy??? Please assist???

[userid]

Hello - I have written a routine in C# that is supposed to replace the MemCpy C++ routine - but the numbers I get are nothing like that displayed in the array below - for the given argument to MemCopy, how is it arriving at the values in elements 0, 1, and 2, below??? Thank you in advance.

memcpy((POINTER)aDataStructure->unsignedLongInt16ElementArray, (POINTER)a20CharacterBufferHoldingTheHome123Value, countOfTen )

Arg1: unsignedLongInt16ElementArray = See below
Arg2: a20CharacterBufferHoldingTheHome123Value = TheHome123
Arg3: countOfTen = 10

Result:
>usignedLongInt16ElementArray[ 0] = 1214605396
>usignedLongInt16ElementArray[ 1] = 828730735
>usignedLongInt16ElementArray[ 2] = 13106
>usignedLongInt16ElementArray[ 3] = 0
>usignedLongInt16ElementArray[ 4] = 0
>usignedLongInt16ElementArray[ 5] = 0
>usignedLongInt16ElementArray[ 6] = 0
>usignedLongInt16ElementArray[ 7] = 0
>usignedLongInt16ElementArray[ 8] = 0
>usignedLongInt16ElementArray[ 9] = 0
>usignedLongInt16ElementArray[10] = 0
>usignedLongInt16ElementArray[11] = 0
>usignedLongInt16ElementArray[12] = 0
>usignedLongInt16ElementArray[13] = 0
>usignedLongInt16ElementArray[14] = 0
>usignedLongInt16ElementArray[15] = 0
>usignedLongInt16ElementArray[16] = 0
>usignedLongInt16ElementArray[17] = 0
>usignedLongInt16ElementArray[18] = 0
>usignedLongInt16ElementArray[19] = 0

[coder777]

How could you mix C# and C++?

memcpy does not use the number of values but the size in bytes of the memory to copy.
I.e. countOfTen * sizeof(*(aDataStructure->unsignedLongInt16ElementArray))

[ThangDo]

wow . such a way to name variables. I have to say way too long.

[userid]

LOL. The naming was to remove any ambiguity for the person assisting me.

[JLBorges]

You can test the correctness of your memcpy with something like this:

using System;
using System.Runtime.InteropServices;
using System.Linq;
using System.Diagnostics;

class name_space
{
    static unsafe void my_memcpy( ulong[] srce, ulong[] dest )
    {
        int nbytes = Math.Min(srce.Length, dest.Length) * sizeof(ulong);
        fixed( ulong* from = srce, to = dest )
        {
            byte* srce_bytes = (byte*)from;
            byte* dest_bytes = (byte*)to;
            for (int i = 0; i < nbytes; ++i) dest_bytes[i] = srce_bytes[i];
        }
    }

    [DllImport("msvcrt.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "memcpy") ]
    static extern UIntPtr libc_memcpy(UIntPtr dest, UIntPtr src, UIntPtr count);

    static void Main(string[] args)
    {
        ulong[] a = { 1, 2, 3, 4, 5 };
        ulong[] b = new ulong[a.Length];
        ulong[] c = new ulong[a.Length];
        ulong[] d = new ulong[a.Length];

        my_memcpy(a,b);

        a.CopyTo(c,0);

        unsafe
        {
            fixed (void* dest = d, srce = a )
            { libc_memcpy((UIntPtr)dest, (UIntPtr)srce, (UIntPtr)(a.Length * sizeof(ulong))); }
        }

        var a_eq_b = Enumerable.SequenceEqual(a, b); // Linq
        var a_eq_c = Enumerable.SequenceEqual(a, c);
        var a_eq_d = Enumerable.SequenceEqual(a, d);

        Debug.Assert(a_eq_b && a_eq_c && a_eq_d);
        Console.Write("all four are equal? " + (a_eq_b && a_eq_c && a_eq_d).ToString() + '\n');
    }
}

[userid]

@Coder777 Thank you. (Not mixing. :-))

@JL Borges Above-and-beyond. Thank you!