我正在尝试使自己熟悉boost::program_options
,并且遇到了位置参数的问题。
这是我的main
函数,我在其中设置通过命令行传递的选项。请注意,这po
是boost::program_options
.
int main(int argc, char** argv)
{
int retval = SUCCESS;
try
{
// Define and parse the program options
po::options_description desc("Options");
desc.add_options()
("help", "Print help messages")
("mode,m", po::value<std::string>()->default_value("ECB"), "cipher mode of operation")
("keyfile,f", po::value<bool>(), "Use keyfile")
("key,k", po::value<std::string>(), "ASCII key")
("infile", po::value<std::string>()->default_value("plaintext.txt"), "input file")
("outfile", po::value<std::string>()->default_value("ciphertext.txt"), "output file");
po::positional_options_description pargd;
pargd.add("infile", 1);
pargd.add("outfile", 2);
po::variables_map vm;
try
{
po::store(po::parse_command_line(argc, argv, desc), vm); // can throw
// --help option
if ( vm.count("help") )
{
std::cout << "Basic Command Line Parameter App" << std::endl
<< desc << std::endl;
return SUCCESS;
}
po::notify(vm); // throws on error, so do after help in case
// there are any problems
}
catch(po::error& e)
{
std::cerr << "ERROR: " << e.what() << std::endl << std::endl;
std::cerr << desc << std::endl;
return ERROR_IN_COMMAND_LINE;
}
///application code here
retval = application(vm);
}
catch(std::exception& e)
{
std::cerr << "Unhandled Exception reached the top of main: "
<< e.what() << ", application will now exit" << std::endl;
return ERROR_UNHANDLED_EXCEPTION;
}
return retval;
} // main
当我尝试使用 打印vm
(variable_map)的位置参数时cout << wm["infile"].as<std::string>();
,我总是得到“infile”参数的默认值。
我正在调用可执行文件./a.out in.file out.file
进行测试。
我究竟做错了什么?