日当周算法的一天？ [英] Date to Day of the week algorithm?

问题描述

什么是算法，赋予了日，月，年，返回星期几？

What is the algorithm that, given a day, month and year, returns a day of the week?

推荐答案

这可以通过完成的<一个href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/mktime.html"><$c$c>std::mktime和<一href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/localtime.html"><$c$c>std::localtime功能。这些功能不仅仅是POSIX，它们是由C ++标准（C ++ 03§20.5）授权。

This can be done using the std::mktime and std::localtime functions. These functions are not just POSIX, they are mandated by the C++ Standard (C++03 §20.5).

#include <ctime>

std::tm time_in = { 0, 0, 0, // second, minute, hour
        4, 9, 1984 - 1900 }; // 1-based day, 0-based month, year since 1900

std::time_t time_temp = std::mktime( & time_in );

// the return value from localtime is a static global - do not call
// this function from more than one thread!
std::tm const *time_out = std::localtime( & time_temp );

std::cout << "I was born on (Sunday = 0) D.O.W. " << time_out->tm_wday << '\n';

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