std::time_get::get_weekday, std::time_get::do_get_weekday - cppreference.com

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# std::time_get::get_weekday, std::time_get::do_get_weekday

From cppreference.com
< cpp‎ | locale‎ | time get

Defined in header `<locale>` |  |
public: iter_type get_weekday( iter_type beg, iter_type end, std::ios_base& str, std::ios_base::iostate& err, std::tm* t) const; | (1) |
protected: virtual iter_type do_get_weekday( iter_type beg, iter_type end, std::ios_base& str, std::ios_base::iostate& err, std::tm* t) const; | (2) |

1) public member function, calls the protected virtual member function `do_get_weekday` of the most derived class.
2) Reads successive characters from the sequence `[beg, end)` and parses out the weekday name (possibly abbreviated), using the default format for weekdays expected by this locale, which is the same format as "%a" as used by the functions std::get_time, `time_get::get`, and the POSIX function `strptime()`

If it finds abbreviated name, followed by the characters that are valid for the full name, it continues reading until it consumes all the characters for the full name or finds a character that isn't expected, in which case parsing fails even if the first few characters were a valid abbreviation.

The parsed weekday is stored in the std::tm field t->tm_wday.

If the end iterator is reached before a valid weekday name is read, the function sets std::ios_base::eofbit in `err`. If a parsing error is encountered, the function sets std::ios_base::failbit in `err`.

### [edit] Parameters

beg | - | iterator designating the start of the sequence to parse
end | - | one past the end iterator for the sequence to parse
str | - | a stream object that this function uses to obtain locale facets when needed, e.g. std::ctype to skip whitespace or std::collate to compare strings
err | - | stream error flags object that is modified by this function to indicate errors
t | - | pointer to the std::tm object that will hold the result of this function call

### [edit] Return value

Iterator pointing one past the last character in `[beg, end)` that was recognized as a part of a valid weekname.

### [edit] Notes

This function is usually case-insensitive.

If a parsing error is encountered, most implementations of this function leave `*t` unmodified.

### [edit] Example

Run this code

    #include <iostream>
    #include <locale>
    #include <sstream>
    #include <iterator>

    void try_get_wday(const std::string& s)
    {
        std::cout << "Parsing the weekday out of '" << s <<
                     "' in the locale " << std::locale().name() << '\n';
        std::istringstream str(s);
        std::ios_base::iostate err = std::ios_base::goodbit;

        std::tm t;
        std::istreambuf_iterator<char> ret =
            std::use_facet<std::time_get<char>>(str.getloc()).get_weekday(
                std::istreambuf_iterator<char>(str),
                std::istreambuf_iterator<char>(),
                str, err, &t
            );
        str.setstate(err);
        if(str) {
            std::cout << "Successfully parsed, weekday number is " << t.tm_wday;
            if(ret != std::istreambuf_iterator<char>()) {
                std::cout << " Remaining content: ";
                std::copy(ret, std::istreambuf_iterator<char>(),
                          std::ostreambuf_iterator<char>(std::cout));
            } else {
                std::cout << " the input was fully consumed";
            }
        } else {
            std::cout << "Parse failed. Unparsed string: ";
            std::copy(ret, std::istreambuf_iterator<char>(),
                      std::ostreambuf_iterator<char>(std::cout));
        }
        std::cout << '\n';
    }
    int main()
    {
        std::locale::global(std::locale("lt_LT.utf8"));
        try_get_wday("Št");
        try_get_wday("Šeštadienis");

        std::locale::global(std::locale("en_US.utf8"));
        try_get_wday("SATELLITE");

        std::locale::global(std::locale("ja_JP.utf8"));
        try_get_wday("土曜日");
    }

Output:

    Parsing the weekday out of 'Št' in the locale lt_LT.utf8
    Successfully parsed, weekday number is 6 the input was fully consumed
    Parsing the weekday out of 'Šeštadienis' in the locale lt_LT.utf8
    Successfully parsed, weekday number is 6 the input was fully consumed
    Parsing the weekday out of 'SATELLITE' in the locale en_US.utf8
    Successfully parsed, weekday number is 6 Remaining content: ELLITE
    Parsing the weekday out of '土曜日' in the locale ja_JP.utf8
    Successfully parsed, weekday number is 6 the input was fully consumed

### [edit] See also

get_time (C++11) | parses a date/time value of specified format (function template) [edit]

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