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| #include <iostream>
#include <string>
#include <boost/program_options.hpp>
using namespace std;
using namespace boost::program_options;
// compile: g++ boostprogramoption.cpp -o boostprogramoption -lboost_program_options
// envs
const string ENVS[] = {
"HOME",
"PKG_CONFIG_PATH",
"PATH",
"http_proxy",
};
const int ENVCOUNT = 4;
static std::string name_mapper(const std::string &var_name){
for (int i = 0; i < ENVCOUNT; ++i) {
if (var_name == ENVS[i])
return var_name;
}
return "";
}
int main(int argc, char** argv)
{
// need to pass the buffer size to constructor (e.g. 1024), otherwise:
// undefined reference to 'boost::program_options::options_description::m_default_line_length'
options_description desc("Allowed options", 1024);
desc.add_options()
("help,h", "produce help message")
("compression,c", value<int>(), "set compression level")
// need to use the env as option, otherwise exception throwed:
("HOME,m", value<string>()->default_value(""), "home dir")
("PATH,p", value<string>()->default_value(""), "path")
("PKG_CONFIG_PATH,k", value<string>()->default_value(""), "pkg config")
("http_proxy", value<string>()->default_value(""), "http proxy");
;
variables_map vm;
store(parse_command_line(argc, argv, desc), vm);
store(parse_environment(desc, name_mapper), vm);
notify(vm);
if (vm.count("help")) {
cout << desc << endl;
return 1;
}
if (vm.count("compression")) {
cout << "Compression level was set to "
<< vm["compression"].as<int>() << endl;
} else {
cout << "Compression level was not set." << endl;
}
for (int i = 0; i < ENVCOUNT; ++i) {
if (vm.count(ENVS[i])) {
cout << ENVS[i] << " is "
<< vm[ENVS[i]].as<string>() << endl;
}
}
return 0;
}
|