Page 39 - DCAP408_WEB_PROGRAMMING

Unit 3: Windows Programming

Notes

Notes Observe that the string passed in lpszCmdLine is not the similar as the string returned
by the GetCommandLine API call. The string in lpszCmdLine comprises the command-line
arguments only (like COMMAND$), but GetCommandLine returns the program name
(counting path) followed by the arguments.

4. nCmdShow: It shows how to exhibit the application’s main window.

Example: The calling application can identify %SW_NORMAL or %SW_MINIMIZE, etc.
It is up to the programmer to respect this parameter, and to do so is suggested.
Return: The return value allocated to WINMAIN is optional, but by convention, the return value
is derived from the wParam& parameter of a %WM_QUIT message.

Usually, a GUI-based application utilizes the WINMAIN function to generate the initial GUI
application window, and then enters a message loop. This loop should end when a %WM_QUIT
message is obtained, and the wParam& parameter of that message should be passed on as the
return value for WINMAIN. If WINMAIN terminates before entering the message loop,
WINMAIN should return zero.
Console applications may utilize the return value to situate an error level that can be passed
back to the calling application, in the range 0 to 255 inclusive. Batch files may perform on the
result through the IF [NOT] ERRORLEVEL batch command.
If the parameters passed to WINMAIN are not needed by the application itself, the PBMAIN
function may be used in position of WINMAIN.
Restrictions: Pointers may not be passed BYREF, so the lpszCmdLine parameter of WINMAIN
must be affirmed to be passed BYVAL.

Example:
#COMPILE EXE
FUNCTION WINMAIN(BYVAL hInst???, BYVAL hPrevInst???, BYVAL pCmdLine AS
WSTRINGZ PTR, BYVAL nCmdShow&) AS LONG
‘ more code here
FUNCTION = 1
END FUNCTION

Task Illustrate the parameters hPrevInst and lpszCmdLine..

Self Assessment

Fill in the blanks:
3. ......................... is a user-defined function called by Windows to start execution of an
application.
4. The ......................... value allocated to WINMAIN is optional, but by convention, the return
value is derived from the wParam& parameter of a %WM_QUIT message.

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