Your application can retrieve the command-line arguments specified when the user started the application; it can also retrieve the current MS-DOS environment.
When a Windows application runs, the Windows startup function copies the command-line arguments to the __argc and __argv variables. Like their counterparts in a standard C application, these variables represent the number of arguments and an array of strings containing the arguments. In addition, the environ variable receives a pointer to an array of strings that contain the current MS-DOS environment at the time the application was started.
To use these variables, you must declare them as external to your application, as follows:
extern int __argc;
extern char ** __argv;
extern char * environ[];You can also retrieve the command-line parameters by parsing the lpszCmdLine parameter, which Windows passes to your application's WinMain function.
If your application does not require access to the command-line arguments or the MS-DOS environment, you can reduce the size of your heap and code by eliminating C run-time initialization code. For information about how to do this, see Section 14.5.10, “Eliminating C Run-Time Startup Code.”
A dynamic-link library (DLL) cannot access the __argc, __argv, and environ variables. Instead, to retrieve the command-line arguments, the library must parse the lpszCmdLine parameter, which Windows passes to the LibEntry function. For more information about LibEntry, see Chapter 20, “Dynamic-Link Libraries.”
Since a dynamic-link library does not have access to the environ variable, it must call the GetDOSEnvironment function to retrieve the environment string.