WinMain 2MWNZB4

The WinMain function is called by the system as the initial entry point for a Win32-based application.

int WINAPI WinMain(

HINSTANCE hInstance,	// handle to current instance
HINSTANCE hPrevInstance,	// handle to previous instance
LPSTR lpCmdLine,	// pointer to command line
int nCmdShow	// show state of window
);

Parameters

hInstance

Identifies the current instance of the application.

hPrevInstance

Identifies the previous instance of the application. For a Win32-based application, this parameter is always NULL. If you need to detect whether another instance already exists, create a named mutex using the CreateMutexJEYQAZ function. If the GetLastError11C2VS7 function returns ERROR_ALREADY_EXISTS, another instance of your application exists (it created the mutex).

lpCmdLine

Points to a null-terminated string specifying the command line for the application.

nCmdShow

Specifies how the window is to be shown. This parameter can be one of the following values:

Value	Meaning
SW_HIDE	Hides the window and activates another window.
SW_MINIMIZE	Minimizes the specified window and activates the top-level window in the system s list.
SW_RESTORE	Activates and displays a window. If the window is minimized or maximized, Windows restores it to its original size and position (same as SW_SHOWNORMAL).
SW_SHOW	Activates a window and displays it in its current size and position.
SW_SHOWMAXIMIZED	Activates a window and displays it as a maximized window.
SW_SHOWMINIMIZED	Activates a window and displays it as an icon.
SW_SHOWMINNOACTIVE	Displays a window as an icon. The active window remains active.
SW_SHOWNA	Displays a window in its current state. The active window remains active.
SW_SHOWNOACTIVATE	Displays a window in its most recent size and position. The active window remains active.
SW_SHOWNORMAL	Activates and displays a window. If the window is minimized or maximized, Windows restores it to its original size and position (same as SW_RESTORE).

Return Values

If the function succeeds, terminating when it receives a WM_QUIT message, it should return the exit value contained in that message s wParam parameter. If the function terminates before entering the message loop, it should return 0.

Remarks

WinMain initializes an application, displays its main window, and then enters a message retrieval-and-dispatch loop that is the top-level control structure for the remainder of the application s execution. The message loop terminates when a WM_QUIT message is received. At that point, WinMain exits the application, returning the value passed in the WM_QUIT message s wParam parameter. If WM_QUIT was received as a result of calling PostQuitMessage, the value of wParam is the value of the PostQuitMessage function s nExitCode parameter. For more information, see Creating a Message LoopDN3.ZJ.