如何获得 Win32 C/C++ 程序的命令行选项？

Question

I have a C/C++ winapi program that I'd like to extend a command line functionality to (which I've seen done in C#, but never C++). If the executable is opened with no arguments, it opens the window as normal, but when called from a command line with arguments such as an input or output file, the window does not open and all user interaction is done through the command line. How could I accomplish this? Preferably I'd like to be able to do it in C, as that's where my WinMain() function is.

Thanks in advance for any help!

Answer 1

There is LPSTR lpCmdLine parameter in WinMain . You can use CommandLineToArgvW function to parse lpCmdLine . When necessary parameters exist, you will not create or show program window and do the job.

Answer 2

There are several ways you can get the (parsed) command line arguments passed to your application.

Entry point

The CRT passes the command line into the user-provided entry point ( WinMain ) as the third argument. Depending on whether your application is compiled for Unicode or not this is either a wide character string or a narrow character string. Using the narrow character version cannot be guaranteed to work when accepting input you do not control. The command line is accepting input you do not control, so you must compile for Unicode (by defining the UNICODE and _UNICODE preprocessor symbols).

Either way, the command line is passed as a single character string. As such it is of limited utility unless you parse out the individual arguments.

Using the Windows API

The Windows API provides the GetCommandLineW function that allows you get a pointer to the command line at any point in your program. Again, this only returns a single character string. The string can be parsed into individual arguments by calling CommandLineToArgvW , producing both an array of arguments as well as its size. Take note that there is no narrow character version of CommandLineToArgvW , so you cannot apply it to the command line argument passed into WinMain if you aren't compiling for Unicode.

Regardless, both of these API calls are available even if you aren't compiling for Unicode.

CRT

If you don't care about portability, Microsoft's CRT implementation provides the __argc, __argv, __wargv global variables, that can be used anywhere in your program to get the parsed command line. While convenient, it depends on the preprocessor symbols defined whether __wargv stores a valid pointer. It only does if _UNICODE is defined.