C++
Date and time using header
Find number of days between two dates
Example
This example shows how to find number of days between two dates. A date is specified by year/month/day of month, and additionally hour/minute/second.
Program calculates number of days in years since 2000.
#include <iostream>
#include <string>
#include <chrono>
#include <ctime>
/***
* Creates a std::tm structure from raw date.
*
* \param year (must be 1900 or greater)
* \param month months since January – [1, 12]
* \param day day of the month – [1, 31]
* \param minutes minutes after the hour – [0, 59]
* \param seconds seconds after the minute – [0, 61](until C++11) / [0, 60] (since C++11)
*
* Based on http://en.cppreference.com/w/cpp/chrono/c/tm
*/
std::tm CreateTmStruct(int year, int month, int day, int hour, int minutes, int seconds) {
struct tm tm_ret = {0};
tm_ret.tm_sec = seconds;
tm_ret.tm_min = minutes;
tm_ret.tm_hour = hour;
tm_ret.tm_mday = day;
tm_ret.tm_mon = month - 1;
tm_ret.tm_year = year - 1900;
return tm_ret;
}
int get_days_in_year(int year) {
using namespace std;
using namespace std::chrono;
// We want results to be in days
typedef duration<int, ratio_multiply<hours::period, ratio<24> >::type> days;
// Create start time span
std::tm tm_start = CreateTmStruct(year, 1, 1, 0, 0, 0);
auto tms = system_clock::from_time_t(std::mktime(&tm_start));
// Create end time span
std::tm tm_end = CreateTmStruct(year + 1, 1, 1, 0, 0, 0);
auto tme = system_clock::from_time_t(std::mktime(&tm_end));
// Calculate time duration between those two dates
auto diff_in_days = std::chrono::duration_cast<days>(tme - tms);
return diff_in_days.count();
}
int main()
{
for ( int year = 2000; year <= 2016; ++year )
std::cout << "There are " << get_days_in_year(year) << " days in " << year << "\n";
}
