How to print value in boost::u32regex & reg

Question

I want to print a value in boost::u32regex & reg using std::cout.

For boost::regex & reg, I can print reg.str() but not able to use str() to boost::u32regex.

Can anyone please tell me ?

Answer 1

It seems that the type used behind boost::u32regex is not compatible with cout. It seems they are using Uchar32 from the ICU library.

You can print your regex value by using iterators :

#include <boost/regex.hpp>
#include <boost/regex/icu.hpp>
#include <unicode/ustream.h>

void PrintRegex32( const boost::u32regex& r )
{
    boost::u32regex::iterator it  = r.begin();
    boost::u32regex::iterator ite = r.end();

    for ( ; it != ite; ++it )
    {
        std::cout << UnicodeString(*it) << std::endl;
    }
}

This is working for me. It is not as easy as printing a boost::regex value but it works. I suggest you to create a function to do so, like in the example.

EDIT :

You can try the code :

boost::u32regex r = boost::make_u32regex("(?:\\A|.*\\\)([^\\\]+)");
PrintRegex32( r );

---

I can print reg.str()

Just for the information, boost::basic_regex has an operator<< overload who are doing exactly the same thing so :

// reg is a boost::regex
std::cout << reg.str() << std::endl;

is the same thing as

// reg is a boost::regex
std::cout << reg << std::endl;