How do I use boost::lexical_cast and std::boolalpha? i.e. boost::lexical_cast< bool >("true")
I'm posting the answer to my own question here for others who may be looking for something like this:
struct LocaleBool {
bool data;
LocaleBool() {}
LocaleBool( bool data ) : data(data) {}
operator bool() const { return data; }
friend std::ostream & operator << ( std::ostream &out, LocaleBool b ) {
out << std::boolalpha << b.data;
return out;
}
friend std::istream & operator >> ( std::istream &in, LocaleBool &b ) {
in >> std::boolalpha >> b.data;
return in;
}
};
usage:
#include <boost/lexical_cast.hpp>
#include <iostream>
#include "LocaleBool.hpp"
int main() {
bool b = boost::lexical_cast< LocaleBool >("true");
std::cout << std::boolalpha << b << std::endl;
std::string txt = boost::lexical_cast< std::string >( LocaleBool( b ) );
std::cout << txt << std::endl;
return 0;
}
In addition to the answer form poindexter, you can wrap the method from here in a specialized version of boost::lexical_cast
:
namespace boost {
template<>
bool lexical_cast<bool, std::string>(const std::string& arg) {
std::istringstream ss(arg);
bool b;
ss >> std::boolalpha >> b;
return b;
}
template<>
std::string lexical_cast<std::string, bool>(const bool& b) {
std::ostringstream ss;
ss << std::boolalpha << b;
return ss.str();
}
}
And use it:
#include <iostream>
#include <boost/lexical_cast.hpp>
//... specializations
int main() {
bool b = boost::lexical_cast<bool>(std::string("true"));
std::cout << std::boolalpha << b << std::endl;
std::string txt = boost::lexical_cast< std::string >(b);
std::cout << txt << std::endl;
return 0;
}
I personally liked this approach because it hides any special code (e.g. using LocaleBool
or to_bool(...)
from the link) for converting to/from bools.