>>>>Hi All,
>>>>
>>>>I have to use Sendmessage Winapi and receive message from opposite application. I found this code from internet:
>>>>
>>>>
>>>>
>>>>

>>>>Declare Long FindWindowA In Win32API String cNULL, String cWinName
>>>>DECLARE LONG SendMessage IN user32 AS WinAPI_SendMessage ; 
>>>>	LONG,; 
>>>>	LONG,; 
>>>>	LONG,; 
>>>>	STRING @
>>>>sTitle = "kl_ecrsunucu"
>>>>iHwnd = FindWindowA(0, sTitle)
>>>>#DEFINE WM_COPYDATA 	0x004A
>>>>*  _vfp.hWnd
>>>>xstr="qqq"
>>>>lnRetVal = WinAPI_SendMessage(ihWnd, WM_COPYDATA, this.HWnd , @xstr)
>>>>WAIT WINDOW lnretval 
>>>>

>>>>
>>>>opposite application look for kl_ecrclient caption at my form. What I should do for receive message after change my forms caption? How can I read message from opposite?
>>>
>>>Metin,
>>>
>>>If you use COPYDATA, then
>>>the string ( xstr ) must respect the format - length is 12 bytes
>>>
>>>
>>>

>>>typedef struct tagCOPYDATASTRUCT {
>>>  ULONG_PTR dwData;	&& any data: The data to be passed to the receiving application
>>>  DWORD     cbData; && The size, in bytes, of the data pointed to by the lpData member
>>>  PVOID     lpData; && The data to be passed to the receiving application. This member can be NULL.	
>>>} COPYDATASTRUCT, *PCOPYDATASTRUCT;
>>>

>>>
>>>dwData : see above
>>>cbData: see above
>>>lpData: since this is a pointer to the data (ie the address, you have to allocate this space with an api - eg HeapAlloc(). Do not forget to free the buffer on exit : HeapFree)
>>>
>>>Sending:
>>>
>>>You can copy data to the allocated lpdata buffer with sys(2600)
>>>
>>>Receive:
>>>

>>>function ReceiveDetailMessage(hwnd, msg, wparam, lparam)
>>>
>>>	local dwdata, cbdata , lpData, s
>>>		
>>>	dwdata = ctobin(Sys(2600, m.lparam+0, 4), '4rs')
>>>	cbdata = ctobin(Sys(2600, m.lparam+4, 4), '4rs')
>>>	lpData = ctobin(Sys(2600, m.lparam+8, 4), '4rs')
>>>	s= sys(2600, m.lpData, m.cbdata )
>>>	
>>>

>>
>>When you saying "length is 12 bytes", what you mean?
>>
>>Thank you,
>
>Your xstr must be exactly 12 bytes - see the COPYDATASTRUCT
>
>( copied from above)
>

>>>typedef struct tagCOPYDATASTRUCT {
>>>  ULONG_PTR dwData;	&& any data: The data to be passed to the receiving application
>>>  DWORD     cbData; && The size, in bytes, of the data pointed to by the lpData member
>>>  PVOID     lpData; && The data to be passed to the receiving application. This member can be NULL.	
>>>} COPYDATASTRUCT, *PCOPYDATASTRUCT;
>>>

>>>
>>>dwData : see above
>>>cbData: see above
>>>lpData: since this is a pointer to the data (ie the address, you have to allocate this space with an api - eg HeapAlloc(). Do not forget to free the buffer on exit : HeapFree)
>
>So
>bytes 1-4 : anything you need - or do not use it
>bytes 4-8 : the length of the string
>bytes 9-12: the address ( or a pointer) of a buffer allocated by HeapAlloc(). -if the length of the strings change, allocate the maximum you will need, and change bytes 4-8 for each message
>
>You put the data starting at the address of the buffer ( allocated with HeapAlloc()) and copy the data using sys(2600)

Thank You All,

And stars goes to Gregory... :)