Convert a unicode String In C++ To Upper Case

Question

How we can convert a multi language string or unicode string to upper/lower case in C or C++.

Answer 1

Set the locale first, example :

setlocale(LC_ALL, "German")); /*This won't work as per comments below */

setlocale(LC_ALL, "English"));

setlocale( LC_MONETARY, "French" );

setlocale( LC_ALL, "" ); //default locale 

Then use

std::use_facet std::locale as follows:-

typedef std::string::value_type char_t;
char_t upcase( char_t ch )
{
 return std::use_facet< std::ctype< char_t > >( std::locale() ).toupper( ch );
}

std::string toupper( const std::string &src )
{
 std::string result;
 std::transform( src.begin(), src.end(), std::back_inserter( result ), upcase );
 return result;
}

const std::string src  = "Hello World!";
std::cout << toupper( src );