std::messages::get, std::messages::do_get

 

C++

Language

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Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Localizations library

Locales and facets
locale
use_facet	has_facet
Character classification
isspace isblank (C++11) iscntrl isupper islower isalpha	isdigit ispunct isxdigit isalnum isprint isgraph
Conversions
toupper tolower	wstring_convert (C++11) wbuffer_convert (C++11)
Facet category base classes
ctype_base codecvt_base messages_base	time_base money_base
Facet categories
ctype ctype<char> codecvt collate messages time_get time_put	num_get num_put numpunct money_get money_put moneypunct
Locale-specific facets
ctype_byname codecvt_byname messages_byname collate_byname	time_get_byname time_put_byname numpunct_byname moneypunct_byname
Code conversion facets
codecvt_utf8 (C++11) codecvt_utf16 (C++11)	codecvt_utf8_utf16 (C++11) codecvt_mode (C++11)
C locale
setlocale localeconv lconv	LC_ALLLC_COLLATELC_CTYPELC_MONETARYLC_NUMERICLC_TIME

 

std::messages

Member functions

messages::messages

messages::~messages

messages::openmessages::do_open

messages::getmessages::do_get

messages::closemessages::do_close

 

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

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.

Parameters

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.

Notes

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.

Example

The following example demonstrated retrieval of messages: on a typical GNU/Linux system it reads from /usr/share/locale/de/LC_MESSAGES/sed.mo

Run this code

#include <iostream>
#include <locale>
 
int main()
{
    std::locale loc("de_DE.utf8");
    std::cout.imbue(loc);
    auto& facet = std::use_facet<std::messages<char>>(loc);
    auto cat = facet.open("sed", loc);
    if(cat < 0 )
        std::cout << "Could not open german \"sed\" message catalog\n";
    else
        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';
    facet.close(cat);
}

Possible output:

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