boost::p rogram_options 在指定意外的位置参数时不报告任何错误

Question

这是一个使用boost解析选项的简单程序：

#include <iostream>
#include <boost/program_options.hpp>
namespace po = boost::program_options;
int main(int argc, char **argv) 
{
try
{
size_t param = std::numeric_limits<size_t>::max();
po::options_description desc("Syntax: [options] "input binary file".nAllowed options:");
desc.add_options()
("help,h", "produce help message")
("param,p", po::value<size_t>(&param), "param");
po::variables_map vm;
po::store(po::parse_command_line(argc, argv, desc), vm);
po::store(po::command_line_parser(argc, argv).options(desc).run(), vm);
po::notify(vm);
if (vm.count("help")) 
{
std::cout << desc << "n";
}
else
{
std::cout << "Running with param " << param << std::endl;
return 0;
}
}
catch(std::exception& e) {
std::cerr << "error: " << e.what() << "n";
}
catch(...) {
std::cerr << "Exception of unknown type!n";
}
return 1;
}

以下是产生的输出：

• hex2txt.exe输出Running with param 0
• hex2txt.exe --param 3输出Running with param 3
• hex2txt.exe --toto输出error: unrecognised option '--toto'

然而，所有这些都是意料之中的：hex2txt.exe foo输出Running with param 0

我本来希望得到一个错误，因为"foo"不是预期的。我在这里做错了什么？

Answer 1

默认情况下接受位置。您可以检查是否未收到任何邮件，也可以指定不允许任何内容：

po::positional_options_description positionals;
po::store(po::command_line_parser(args.size(), args.data())
.options(desc)
.positional(positionals)
.run(),

演示

住在科里鲁

#include <boost/program_options.hpp>
#include <iostream>
#include <iomanip>
namespace po = boost::program_options;
int main() {
std::vector<char const*> const cases[] = {
{ "hex2txt.exe" }, // outputs Running with param 0
{ "hex2txt.exe", "--param", "3" }, // outputs Running with param 3
{ "hex2txt.exe", "--toto" }, // outputs error: unrecognised option '--toto'
// All this is expected, however:
{ "hex2txt.exe", "foo" }, // outputs Running with param 0
};
for (auto args : cases) {
std::cout << "------";
for (auto arg : args)
std::cout << " " << std::quoted(arg);
std::cout << "n";
try {
size_t param = 0; // std::numeric_limits<size_t>::max();
po::options_description desc(
"Syntax: [options] "input binary file".nAllowed options:");
desc.add_options()("help,h", "produce help message")(
"param,p", po::value<size_t>(&param), "param");
po::positional_options_description positionals;
po::variables_map vm;
po::store(po::command_line_parser(args.size(), args.data())
.options(desc)
.positional(positionals)
.run(),
vm);
po::notify(vm);
if (vm.count("help")) {
std::cout << desc << "n";
} else {
std::cout << "Running with param " << param << std::endl;
//return 0;
}
} catch (std::exception const& e) {
std::cerr << "error: " << e.what() << "n";
} catch (...) {
std::cerr << "Exception of unknown type!n";
}
}
}

指纹

------ "hex2txt.exe"
Running with param 0
------ "hex2txt.exe" "--param" "3"
Running with param 3
------ "hex2txt.exe" "--toto"
error: unrecognised option '--toto'
------ "hex2txt.exe" "foo"
error: too many positional options have been specified on the command line