Am I understanding getopt() correctly?

问题

I'm trying to scan the command line for certain letters, symbols and values. I want to scan for "-w", a number, and "-s". I got a response in my last question, I was told to use getopt() and after a little bit of Googling, I think I might get it, but I'm not sure.

This is what I think I'm doing:

int c = 0; 
int b = argv[2];

while((c = getopt(argc, argv, "-w", "-s", b))

I think I'm scanning argc for "-w", "-s" and the argv[2] value (which is the number). But I do not know if I am using it correctly?

回答1:

Your while loop should be while ((c = getopt(argc, argv, "w:s:"))

: the colon means it needs an argument. now convert optarg to an integer or whatever you wanted.

回答2:

int number = 0;
int sflag = 0;
int opt;

while ((opt = getopt(argc, argv, "w:s")) != -1)
{
    switch (opt)
    {
    case 's':
        sflag = 1;
        break;
    case 'w':
        number = atoi(optarg);
        break;
    default:
        /* Report usage and exit? */
        break;
    }
}

The conversion on the number is lazy; you can do more a more careful job calling a function that calls strtol(), for instance. You might need to have a wflag variable that you set analogously to the sflag variable so that you can distinguish -w 0 from 'no -w option specified on the command line'.

来源：https://stackoverflow.com/questions/13767888/am-i-understanding-getopt-correctly