SendMessage(lnCallMeHWnd,WM_COPYDATA, 0,@m.lcText)

string sendString = 测试发送数据;
byte[] sarr = System.Text.Encoding.Default.GetBytes(sendString);
int len = sarr.Length;
COPYDATASTRUCT cds;
cds.dwData = (IntPtr)0 ;
cds.cbData = len + 1;
cds.lpData = sendString;
SendMessage(hWnd, WM_COPYDATA, 0, ref cds);


接收方：
if (m.Msg == WMA_InterPro)
{
COPYDATASTRUCT cds = new COPYDATASTRUCT();
Type t = cds.GetType();
cds = (COPYDATASTRUCT)m.GetLParam(t);
string receiveInfo=cds.lpData;
}

消息的发送和接收，按消息的定义操作就可以。

OK SYS(2600

示例：

#define MY_MESSAGE    0x401
DECLARE long SendMessage IN user32 long,long,string@,long
of = CREATEOBJECT("form1")
of.show(1)

DEFINE CLASS form1 as Form
    ADD OBJECT msg as textbox       WITH left=10, top=10,width=200
    ADD OBJECT cmd as commandbutton WITH left=220,top=10,height=22,caption="发送"
    ADD OBJECT txt as editbox       WITH left=10, top=42,width=200,height=200
    PROCEDURE init
        BINDEVENT(this.hWnd, MY_MESSAGE, this, "onMessage") 
    ENDPROC
    PROCEDURE onMessage(hWnd,msg,wParam,lParam)
        this.txt.SelText = "接收：" + SYS(2600,wParam,lParam)
    ENDPROC
    PROCEDURE cmd.click
        msg = thisform.msg.value
        thisform.txt.value = "发送：" + msg+0h0D0A
        SendMessage(thisform.hWnd, MY_MESSAGE, @msg, LEN(msg))
    ENDPROC
ENDDEFINE

[此贴子已经被作者于2023-7-28 10:48编辑过]

VERY GOOD

//这段代码的功能就是枚举当前所有的顶层窗口句柄，并且指定了一个窗口句柄，如果枚举到的顶层窗口句柄和传递给EnumWindowsProc函数的窗口句柄不同，则使枚举到的顶层窗口失能//自定义结构体
typedef struct _DLONG
{
LONG wParam;
LONG lParam;
}stLONG;

//回调函数的定义
BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
stLONG *pDlong = (stLONG*)lParam;
BOOL bEnable = (BOOL)pDlong->lParam;
if (hwnd != (HWND)pDlong->wParam)
　　EnableWindow(hwnd, bEnable);//如果当前所枚举到的顶层窗口句柄和主调函数(EnumWindos函数)所传递来的额外信息做指定的顶层窗口句柄不同，则进行相关使能或使失能操作
return TRUE;
}

......

stLONG dlong;
//传递给EnumWindowsProc的额外信息
dlong.lParam = (LPARAM)FALSE;
dlong.wParam = (WPARAM)hWnd;
EnumWindows(EnumWindowsProc, (LONG)&dlong);


这种回调怎么写

vfp没有函数指针的概念，要借助其他编程语言实现函数指针来调用vfp的函数。
枚举窗口可以不用 EnumWindows() ，遍历主窗口和子窗口就可以。