program_options

【program_options】

　　The program_options library allows program developers to obtain program options, that is (name, value) pairs from the user, via conventional methods such as command line and config file.

1、添加 options_description.

// Declare the supported options.
po::options_description desc("Allowed options");
desc.add_options()
    ("help", "produce help message")
    ("compression", po::value<int>(), "set compression level")
;

po::variables_map vm;
po::store(po::parse_command_line(ac, av, desc), vm);
po::notify(vm);

if (vm.count("help")) {
    cout << desc << "\n";
    return 1;
}

if (vm.count("compression")) {
    cout << vm["compression"].as<int>() << ".\n";
}

　　使用示例：

　　

2、po::value

int opt;
po::options_description desc("Allowed options");
desc.add_options()
    ("help", "produce help message")
    ("optimization", po::value<int>(&opt)->default_value(10), 
  "optimization level")
    ("include-path,I", po::value< vector<string> >(), 
  "include path")
    ("input-file", po::value< vector<string> >(), "input file")
;

　　使用示例：
　　

3、po::positional_options_description

po::positional_options_description p;
p.add("input-file", -1);

po::variables_map vm;
po::store(po::command_line_parser(ac, av).
          options(desc).positional(p).run(), vm);
po::notify(vm);

　　

4、

参考：

1、https://www.boost.org/doc/libs/1_69_0/doc/html/program_options.html