An application sends the WM_COPYDATA message to pass data to another application.
#define WM_COPYDATA 0x004A
A handle to the window passing the data.
A pointer to a COPYDATASTRUCT structure that contains the data to be passed.
If the receiving application processes this message, it should return TRUE; otherwise, it should return FALSE.
The data being passed must not contain pointers or other references to objects not accessible to the application receiving the data.
While this message is being sent, the referenced data must not be changed by another thread of the sending process.
The receiving application should consider the data read-only. The lParam parameter is valid only during the processing of the message. The receiving application should not free the memory referenced by lParam. If the receiving application must access the data after SendMessage returns, it must copy the data into a local buffer.
For an example, see Using Data Copy.
|Minimum supported client
||Windows 2000 Professional [desktop apps only]
|Minimum supported server
||Windows 2000 Server [desktop apps only]