关于c++向c#传送字符串的问题

关于c++向c#传送字符串的问题

我在C程序里代码如下
HWND   hWnd   =   FindWindow(NULL,_T("WawaApp"));
char *str = new char[3];
str = "123";
SendMessage(hWnd,WM_WAWADEFMSG,(WPARAM)str,strlen(str));
c#代码如下
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern int RegisterWindowMessage(string lpString);

private readonly int WM_WAWADEFMSG = RegisterWindowMessage("WawaDefMsg");
public Form1()
{
    InitializeComponent();
}

protected override void WndProc(ref   Message m)
{
    if(m.Msg ==  WM_WAWADEFMSG)
    {
        int len = m.LParam.ToInt32();
        string str = Marshal.PtrToStringUni(m.WParam, len );
        MessageBox.Show(str);
        return;
    }
    base.WndProc(ref m);
}
可怎么也得不到c里面传过来的值，C里面我用PostMessage和SendMessage都试过了，c#里用 Marshal.PtrToStringUni，Marshal.PtrToStringAnsi,Marshal.PtrToStringAuto等也都试过了，都不行。 --------------------编程问答-------------------- 我改成下面这样也不行，是不是进程间的指针不一样呀。
char *str = new char[3];
strcpy(str,"123"); --------------------编程问答-------------------- 用SendMessage不能传指针，因为指针是指向本身进程的某个地址，跨进程传递的时候，传过去的是本进程的某个地址，而目标进程是不能访问本进程地址空间的，会出错。 --------------------编程问答-------------------- c代码如下
const UINT WM_WAWADEFMSG = ::RegisterWindowMessage(_T("WawaDefMsg"));

int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
{
int nRetCode = 0;

// 初始化 MFC 并在失败时显示错误
if (!AfxWinInit(::GetModuleHandle(NULL), NULL, ::GetCommandLine(), 0))
{
// TODO: 更改错误代码以符合您的需要
_tprintf(_T("错误: MFC 初始化失败\n"));
nRetCode = 1;
}
else
{
LPCWSTR str = _T("hello中国！");
int id = GlobalFindAtom(str);
HWND   hWnd   =   FindWindow(NULL,_T("WawaApp"));
if(id == 0)
{
id = GlobalAddAtom(str);
}
SendMessage(hWnd,WM_WAWADEFMSG,id,lstrlen(str));
}

return nRetCode;
}
c#代码如下
    public partial class Form1 : Form
    {
        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern int RegisterWindowMessage(string lpString);

        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        public static extern long GlobalGetAtomName(Int32 atom, StringBuilder lpBuffer, int size);

        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        public static extern Int32 GlobalDeleteAtom(Int32 atom);

        private readonly int WM_WAWADEFMSG = RegisterWindowMessage("WawaDefMsg");
        public Form1()
        {
            InitializeComponent();
        }

        protected override void WndProc(ref   Message m)
        {
            if(m.Msg ==  WM_WAWADEFMSG)
            {
                int atom = m.WParam.ToInt32();
                int len = m.LParam.ToInt32();
                StringBuilder buffer = new StringBuilder(len);
                GlobalGetAtomName(atom, buffer, len);
                MessageBox.Show(buffer.ToString());
                GlobalDeleteAtom(atom);
                return;
            }
            base.WndProc(ref m);
        }
    }

补充：.NET技术 ,  C#