根据日期计算周数
问题：
给定一个日期，确定周数年内的那个日期。例如，2008年，1月1日至1月6日为第1周，1月7日至13日为第2周。如果日期是2008年1月10日，则相应的周数应为2。
ISO 8601 标准：
请记住，一年中的“第 n”周可能会有所不同。 ISO 8601 标准定义了周编号的具体准则：
实现：
以下 C 语言代码示例演示了如何根据 ISO 8601 标准计算周数：
#include <chrono>
#include <iostream>
using namespace std;
class Date {
private:
int year;
int month;
int day;
public:
Date(int year, int month, int day) : year(year), month(month), day(day) {}
int getWeekNumber() {
// Convert the date to a system_time object
time_t t = time(0);
tm* timeinfo = localtime(&t);
// Create a system_time object for the first day of the year
tm first_of_year;
first_of_year.tm_year = year - 1900;
first_of_year.tm_mon = 0;
first_of_year.tm_mday = 1;
time_t first_of_year_time = mktime(&first_of_year);
// Calculate the number of days between the first day of the year and the given date
long days_since_first_of_year = difftime(t, first_of_year_time) / (60 * 60 * 24);
// Calculate the week number based on the number of days since the first day of the year
int week_number = 1 + (days_since_first_of_year / 7);
// Adjust the week number for possible week 53
int days_in_year = days_since_first_of_year + 1;
int days_in_last_week = days_in_year % 7;
if (days_in_last_week >= 5 && (week_number == 53 || (week_number == 52 && days_in_year >= 371))) {
week_number = 53;
}
return week_number;
}
};
int main() {
Date date(2008, 1, 10);
cout << "Week number for January 10th 2008 is: " << date.getWeekNumber() << endl;
return 0;
}输出：
Week number for January 10th 2008 is: 2
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