# std::messages::get, do_get

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< cpp‎ | locale‎ | messages

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);
    }

Output:

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

### See also

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