Programatically close an MFC message box

Create a Messagebox by applying its caption
for Example ::Messagebox(hWnd,"TEXT","YOURTITLE",MB_OK);

Now from other thred find window like
HWND hWnd = ::FindWindow(NULL,"YOURTITLE");
if(hWnd)
{
::PostMessage(hWnd,WM_CLOSE,0,0);

}

If you are referring to AfxMessageBox, no. You need to click in a button or close it with the "x" manually.

if you want your programm to close your MessageBox then it should create it before, meaning you need to do your own one.

Not sure what you mean. If you call AfxMessageBox, you will be blocked there until the user closes it. How can you even issue a request to close that message box? Unless you have a backgound thread...

Create a Messagebox by applying its caption
for Example ::Messagebox(hWnd,"TEXT","YOURTITLE",MB_OK);

Now from other thred find window like
HWND hWnd = ::FindWindow(NULL,"YOURTITLE");
if(hWnd)
{
::PostMessage(hWnd,WM_CLOSE,0,0);

}