Revising the WinMain Function
You need to revise the WinMain function if either of the following is true:
Your application needs to know when another instance of the application is running, or
You need to access the command line.
Otherwise, the code in this function generally needs no change.
The parameter list for WinMain is the same for Win32 and Windows 3.x:
int PASCAL WinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow)
Note that under Win32, the hPrevInstance parameter is always passed NULL (see the next section, Initializing Instances). As with 16-bit Windows 3.x, the lpCmdLine parameter points to a string containing the entire command line.