std::time_g...do_get_time(3)

💖 std::time_g...do_get_time(3) 💖

okay so bestie, this one is from the C++ Standard Libary manual (yes, that's how the header spells it, and we are not fixing it — character-for-character energy 💅). It's all about std::time_get::get_time and std::time_get::do_get_time, aka the C++ locale girlies who parse times out of character sequences. No cap.

✨ NAME ✨

std::time_get::get_time,std::time_get::do_get_time — std::time_get::get_time,std::time_get::do_get_time

🌸 SYNOPSIS 🌸

Defined in header <locale>
public:

iter_type get_time( 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_time( iter_type beg, iter_type end,
                               std::ios_base& str,
                               std::ios_base::iostate& err, std::tm* t ) const;
(2)

(1) is the public member function — it literally calls the protected virtual member function do_get_time of the most derived class.

(2) is the protected virtual one: it reads successive characters from the sequence [beg, end) and parses out the time value following the same rules as the format specifier "%H:%M:%S" as used by the functions std::get_time, time_get::get, and the POSIX function strptime().

The parsed time is stored in the corresponding fields of the std::tm structure pointed to by the argument t.

If the end iterator is reached before a valid time 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.

🎀 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.
• 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.

✨ RETURN VALUE ✨

Iterator pointing one past the last character in [beg, end) that was recognized as a part of a valid date. (Yes, it says date — we're keeping the original wording, bestie, details are sacred.)

🦋 NOTES 🦋

For the alphabetic components of the default time format (if any), this function is usually case-insensitive.

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

💅 EXAMPLE 💅

// Run this code

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

void try_get_time(const std::string& s)
{
    std::cout << "Parsing the time 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::time_get<char> const& facet =
        std::use_facet<std::time_get<char>>(str.getloc());
    std::istreambuf_iterator<char> ret =
        facet.get_time({str}, {}, str, err, &t);
    str.setstate(err);

    if (str)
    {
        std::cout << "Hours: " << t.tm_hour << ", "
                     "Minutes: " << t.tm_min  << ", "
                     "Seconds: " << t.tm_sec  << '\n';
    }
    else
    {
        std::cout << "Parse failed. Unparsed string: ";
        std::copy(ret, {}, std::ostreambuf_iterator<char>(std::cout));
        std::cout << '\n';
    }
}

int main()
{
    std::locale::global(std::locale("ru_RU.utf8"));
    try_get_time("21:40:11");
    try_get_time("21-40-11");

    std::locale::global(std::locale("ja_JP.utf8"));
    try_get_time("21時37分58秒");
}

Output:

Parsing the time out of '21:40:11' in the locale ru_RU.utf8
Hours: 21, Minutes: 40, Seconds: 11
Parsing the time out of '21-40-11' in the locale ru_RU.utf8
Parse failed. Unparsed string: -40-11
Parsing the time out of '21時37分58秒' in the locale ja_JP.utf8
Hours: 21, Minutes: 37, Seconds: 58

🔥 DEFECT REPORTS 🔥

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

• DR LWG 248 — Applied to: C++98; Behavior as published: eofbit was not set upon reaching the end iterator; Correct behavior: sets eofbit if a valid time has not been read.
• DR LWG 461 — Applied to: C++98; Behavior as published: do_get_time needed to parse localized time representation; Correct behavior: parses with "%H:%M:%S" format.

👑 SEE ALSO 👑

• get_time — parses a date/time value of specified format — (C++11) — (function template)

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okay that's the whole page, bestie. Source: http://cppreference.com — version/date: 2024.06.10. Go parse those times and slay 💖✨