getopt()

This is a discussion on getopt() within the Linux Programming forums, part of the Platform Specific Boards category; i have problems using the getopt(). Code: ... char lala, test[2]; while((lala = getopt(argc, argv, "m:S:")) != EOF) { switch(lala) ...

  1. #1
    template<typename T> threahdead's Avatar
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    Sep 2002
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    214

    getopt()

    i have problems using the getopt().
    Code:
    ...
    
    char lala, test[2];
    
    while((lala = getopt(argc, argv, "m:S:")) != EOF)
    {
       switch(lala)
       {
          case 'm':
          {
              printf("%s\n", optarg);
              ....
              break;
          }
    
          case 'S':
          {
              printf("%s\n", optarg);
              sscanf(optarg, "%x:%x", test[0], test[1]);
              break;
          }
          
         default: break;
        }
    }
    when i use printf() to print the optarg of case S, it tells me that it is (null).
    so i get a segmentation violation.
    why is optarg (null)?

    thanks

  2. #2
    template<typename T> threahdead's Avatar
    Join Date
    Sep 2002
    Posts
    214
    Originally posted by vVv
    getopt( ) returns int, not char.
    so what i am supposed to change?

    lets assume i run the code like that:

    Code:
    ./program -m printit -S ff:ff
    output:
    
    printit
    SIGSEGV
    as it seems there is no problem with printing the string "printit" for case 'm'.
    but why is optarg = null in case S only?

    thanks

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