Comments on: 7.13 — Command line arguments

By: Alex

Alex — Fri, 11 Jul 2008 02:10:12 +0000

argv is of type char *argv[], which is essentially a pointer to a pointer.

When we use the array index operator [] on a pointer/array, there is an implicit dereference that happens. If argv is of type char *argv[], then argv[1] is of type char*, which is what we’ve declared pFilename as.

By: Astro

Astro — Thu, 10 Jul 2008 16:22:04 +0000

Should "char *pFilename = argv[1];" in the example above be "char *pFilename = &argv[1];" ????

Am I confusing myself here?

By: Alex

Alex — Sat, 31 May 2008 00:36:30 +0000

I think this has something to do with the way your program is doing character encoding. TCHAR is a macro that can resolve to either char or wchar_t depending on whether or not you are using wide characters. If you are using wide characters (wchar_t), then trying to use cout to print them will print addresses instead of values because it doesn’t know how to handle them. My guess is that _tmain() is converting your command line parameters to wide character strings, but main() isn’t.

By: Doug

Doug — Tue, 20 May 2008 00:21:51 +0000

You have a GREAT site! I am using Visual Studio 2008 and it has been working great up until now. If I use the built in "_tmain" declaration, I get 4 addresses printed. But when I use your declaration, it works perfect. What is the difference in the declarations?

int _tmain(int argc, _TCHAR* argv[])
//int main(int argc, char *argv[])   
{   
    using namespace std;   
  
    cout << "There are " << argc << " arguments:" << endl;   
  
    // Loop through each argument and print its number and value   
    for (int nArg=0; nArg < argc; nArg++)   
        cout << nArg << " " << argv[nArg] << endl;   
  
    return 0;   
}

By: kingyo

kingyo — Sun, 23 Mar 2008 20:47:35 +0000

Really nice job, helped me a lot…
Thank you!

By: programmer in training

programmer in training — Tue, 11 Mar 2008 06:43:09 +0000

I though the final example is suppose to be main(int argc, char *argc) instead of just int main()??

[ It is indeed. -Alex ]