How to cast string with comma to double using boost

Question

it is possible to do something like that

std::string str = "127,8";
double x = boost::lexical_cast<double>(str);

I tried it but it throws an exception, do u have a simple way to do such cast using boost ?

Answer 1

You can use a custom locale that uses , for the decimal point. Code taken and modified from https://stackoverflow.com/a/7277333/4117728

#include <iostream>
#include <boost/lexical_cast.hpp>
class comma_numpunct : public std::numpunct<char>
{
  protected:
    virtual char do_decimal_point() const
    {
        return ',';
    }


};

int main(int argc, char *argv[]) {
    std::string str = "127,8";
    std::locale comma_locale(std::locale(), new comma_numpunct());
    std::locale::global(comma_locale);
    double x = boost::lexical_cast<double>(str);
}