std::messages<CharT>::get,std::messages<CharT>::do_get (3) - Linux Manuals

std::messages<CharT>::get,std::messages<CharT>::do_get: std::messages<CharT>::get,std::messages<CharT>::do_get


std::messages<CharT>::get,std::messages<CharT>::do_get - std::messages<CharT>::get,std::messages<CharT>::do_get


Defined in header <locale>
public: (1)
string_type get( catalog cat, int set, int msgid, const string_type& dfault ) const;
protected: (2)
virtual string_type do_get( catalog cat, int set, int msgid, const string_type& dfault ) const;

1) Public member function, calls the protected virtual member function do_get of the most derived class.
2) Obtains a message from the open message catalog cat using the values set, msgid and dfault in implementation-defined manner. If the expected message is not found in the catalog, returns a copy of dfault.


cat - identifier of message catalog obtained from open() and not yet passed to close()
set - implementation-defined argument, message set in POSIX
msgid - implementation-defined argument, message id in POSIX
dfault - the string to look up in the catalog (if the catalog uses string look-up) and also the string to return in case of a failure

Return value

The message from the catalog or a copy of dfault if none was found.


On POSIX systems, this function call usually translates to a call to catgets(), and the parameters set, msgid, and dfault are passed to catgets() as-is. In GNU libstdc++, this function ignores set and msgid and simply calls GNU gettext(dfault) in the required locale.


The following example demonstrated retrieval of messages: on a typical GNU/Linux system it reads from /usr/share/locale/de/LC_MESSAGES/
// Run this code

  #include <iostream>
  #include <locale>

  int main()
      std::locale loc("de_DE.utf8");
      auto& facet = std::use_facet<std::messages<char>>(loc);
      auto cat ="sed", loc);
      if(cat < 0 )
          std::cout << "Could not open german \"sed\" message catalog\n";
          std::cout << "\"No match\" in German: "
                    << facet.get(cat, 0, 0, "No match") << '\n'
                    << "\"Memory exhausted\" in German: "
                    << facet.get(cat, 0, 0, "Memory exhausted") << '\n';

Possible output:

  "No match" in German: Keine Übereinstimmung
  "Memory exhausted" in German: Speicher erschöpft

See also