An application sends an EM_GETLINECOUNT message to retrieve the number of lines in a multiline edit control.
EM_GETLINECOUNT wParam = 0; // not used; must be zero lParam = 0; // not used; must be zero
This message has no parameters.
The return value is an integer specifying the number of lines in the multiline edit control. If no text is in the edit control, the return value is 1.