How do I write a command help in C++?

It is preferable to use class that comes from ACE library, ACE_Get_Opt: http://www.dre.vanderbilt.edu/Doxygen/Current/html/ace/classACE__Get__Opt.html

Here there is a brief example of use:

#include <ARGV.h>
#include <ace/Arg_Shifter.h>
#include <ace/Get_Opt.h>

....

  ACE_Get_Opt get_opts (argc, &argv[1], "db:");

  ACE_CString m_b_arg_string("");
  int m_a_arg_int = -1;
 
  // the third parameter can be ACE_Get_Opt::ARG_REQUIRED, ACE_Get_Opt::ARG_OPTIONAL or without 3rd argument for a no argument.
  if (get_opts.long_option(ACE_TEXT ("a_long_option"), 'a', ACE_Get_Opt::ARG_REQUIRED) == -1)
    return -1;
  if (get_opts.long_option(ACE_TEXT ("another_long_option"), 88) == -1)
    return -1;
  if (get_opts.long_option(ACE_TEXT ("help"), h) == -1)
    return -1;
  int c;
  while ((c = get_opts ()) != -1)
    switch (c)
      {
      case 'd':
          //do something
          break;
      case 'b':
          m_b_arg_string = ACE_CString(get_opts.optarg);
          //do something else
          break;
      case 'a':
          //always check if the value is numeric if that is needed
          if(isNumeric(get_opts.optarg))
             m_a_arg_int = atoi(get_opts.optarg);
          else 
             showUsage(argc, argv);
          break;
      case 88:
          //do something
          break;
      case '?':
          //this case informs when the option, that needs an argument, doesn't have it.
          ACS_SHORT_LOG((LM_INFO, MyProgram::main: Option -%c requires an argument!", get_opts.opt_opt()));
          return -1;
      case 'h':
      default:
         showUsage(argc, argv);
       }

-- CarlitaParedes - 27 Jun 2006