Develop Reference

Time difference from anywhere in the world

On my website i want to ensure if the time gap is under 1 minute of DateTime st of the below function, an action can be taken otherwise it would be declined. Here's the code for that
DateTime st = MyDate.Value; // current value from database: 2019-12-05 13:20:15.478
DateTime now = DateTime.Now;
TimeSpan span = now.Subtract(st);
int expMin = 1;
if (span.Minutes < expMin)
{
// Do something
}
else
{
// Ignore
}
So based on the above date value the service cant be accessed after 2019-12-05 13:21:15.478
This works locally and on my server but I've seen some reports where some users are accessing the service from another country. Is there another way i should be ensuring the time, no matter which country the user is from, can't be accessed after the one minute timespan?

You need to use DateTimeOffset to consider the timezone of your users.
I assume that "MyDate" is passed by the client. See the following example.
var myDate = new DateTimeOffset(2019, 12, 05, 13, 20, 15, 478, new TimeSpan(0, 2, 0, 0, 0));
var now = new DateTimeOffset(2019, 12, 05, 14, 20, 45, 478, new TimeSpan(0, 3, 0, 0, 0));
var span = now.Subtract(myDate);
int expMin = 1;
if (span.Minutes < expMin)
{
Console.WriteLine("Do something");
}
else
{
Console.WriteLine("Ignore");
}

Round DateTime nearest nth minute

I'm trying to round a DateTime to the nearest 7 minute.
I've seen many rounding functions for c#, but for some reason, I'm getting different results to what I'm expecting.
Given the following time:
var d = new DateTime(2019, 04, 15, 9, 40, 1, 0);
If I want to round to the nearest 7th minute then I would expect the answer to be
2019-04-15 9:42:00 // 0, 7, 14, 21, 28, 35, 42 ?
Input / Expected result
new DateTime(2019, 04, 15, 9, 40, 0, 0); // 9:42
new DateTime(2019, 04, 15, 9, 03, 0, 0); // 9:07
new DateTime(2019, 04, 15, 9, 31, 0, 0); // 9:35
new DateTime(2019, 04, 15, 9, 21, 0, 0); // 9:21
new DateTime(2019, 04, 15, 9, 0, 0, 0); // 9:00
new DateTime(2019, 04, 15, 9, 58, 0, 0); // 10:00 (start again)
Various DateTime rounding functions that I've seen show the following answers, which I can't understand why unless I'm missing something
9:41 or
9:43
Example of rounding functions
public static DateTime RoundUp(this DateTime dt, TimeSpan d)
{
var modTicks = dt.Ticks % d.Ticks;
var delta = modTicks != 0 ? d.Ticks - modTicks : 0;
return new DateTime(dt.Ticks + delta, dt.Kind);
}
DateTime RoundUp(DateTime dt, TimeSpan d)
{
return new DateTime((dt.Ticks + d.Ticks - 1) / d.Ticks * d.Ticks, dt.Kind);
}

static DateTime RoundUpNMinute(DateTime dt, int n)
{
var minute = dt.Minute;
if (minute % n == 0)
return dt;
var minuteRoundUp = minute / n * n + n;
if(minuteRoundUp > 60)
return new DateTime(dt.Year, dt.Month, dt.Day, dt.Hour, 0, 0, dt.Kind).AddHours(1);
else
return new DateTime(dt.Year, dt.Month, dt.Day, dt.Hour, minuteRoundUp, 0, dt.Kind);
}
Got same results for all your examples.

Find hole in schedule

I’m looking for a way to find holes in a schedule, times that does not have a booking.
I have a simple class in C# that looks like:
DateTime StartTime { get; set; }
Datetime EndTime { get; set; }
public int User_ID { get; set; }
The same class is used for the bookings aswell.
Let’s assume I have these objects:
Schedule: StartTime "2017-03-14 08:00" - EndTime "2017-03-14 16:00" (8 hours)
Booking: StartTime "2017-03-14 09:00" - Endtime "2017-03-14 10:00" (1 hour)
My final result from this would be 2 objects that represents the “free time”:
Free: StartTime "2017-03-14 08:00" EndTime: "2017-03-14 09:00" (1 hour)
Free: StartTime "2017-03-14 10:00" EndTime: "2017-03-14 16:00"(6 hour)
How would I check this in C#?
I'm thinking about looping the Schedule and split them on start/end of each booking, but I'm not sure how to do it.

It is easier than I thought... Note that this code isn't optimized, and this algorithm isn't probably very optimizable:
public class TimeSegment
{
public readonly DateTime StartTime;
public readonly DateTime EndTime;
public TimeSegment(DateTime startTime, DateTime endTime)
{
StartTime = startTime;
EndTime = endTime;
}
public TimeSegment[] Subtract(TimeSegment other)
{
// 8-10 Subtract 10-11 = 8-10
if (StartTime > other.EndTime || other.StartTime > EndTime)
{
// If there is no intersection, we return { this }
// (no subtraction)
return new[] { this };
}
if (StartTime >= other.StartTime)
{
// 8-10 Subtract 8-10 = (nothing)
// 8-10 Subtract 7-11 = (nothing)
if (EndTime <= other.EndTime)
{
// Total subtraction, nothing remains!
return new TimeSegment[0];
}
else
{
// 8-10 Subtract 7-9 = 9-10
return new[] { new TimeSegment(other.EndTime, EndTime) };
}
}
// 8-12 Subtract 9-13 = 8-9
if (EndTime <= other.EndTime)
{
return new[] { new TimeSegment(StartTime, other.EndTime) };
}
// 8-12 Subtract 9-11 = 8-9, 11-12
// Complete case: two TimeSegments returned
return new[] { new TimeSegment(StartTime, other.StartTime), new TimeSegment(other.EndTime, EndTime) };
}
public override string ToString()
{
return string.Format("{0}-{1}", StartTime, EndTime);
}
}
And then:
var schedules = new List<TimeSegment> { new TimeSegment(new DateTime(2017, 03, 14, 08, 00, 00), new DateTime(2017, 03, 14, 16, 00, 00)) };
var bookings = new List<TimeSegment>
{
new TimeSegment(new DateTime(2017, 03, 14, 09, 00, 00), new DateTime(2017, 03, 14, 10, 00, 00)),
new TimeSegment(new DateTime(2017, 03, 14, 12, 00, 00), new DateTime(2017, 03, 14, 14, 00, 00)),
new TimeSegment(new DateTime(2017, 03, 14, 13, 00, 00), new DateTime(2017, 03, 14, 15, 00, 00)),
};
foreach (TimeSegment booking in bookings)
{
var schedulesNew = new List<TimeSegment>();
foreach (TimeSegment schedule in schedules)
{
var diff = schedule.Subtract(booking);
schedulesNew.AddRange(diff);
}
schedules = schedulesNew;
}
There "core" of this is a Subtract function that given a TimeSegment subtracts from this another TimeSegment, returning 0, 1 or 2 TimeSegments... Then iteratively we subtract all the bookings from the TimeSegments that we produced from the previous booking.

Count number of including weeks between 2 dates

I need to get the number of weeks between 2 dates.
A week for me is monday to sunday.
So if the first date is on a saturday than this week should be included.
if the second date is on a monday than this week should be included.
What is the most efficient way to do this ?
example :
startdate enddate nbr of weeks
17/09/2016 26/09/2016 3 weeks
17/09/2016 25/09/2016 2 weeks
19/09/2016 26/09/2016 2 weeks
12/09/2016 25/09/2016 2 weeks
I found much answers for this, like this one for example how to calculate number of weeks given 2 dates? but they all end up with dividing the days with 7 and that does not gives the result I need.

The simplest way is probably to write a method to get the start of a week. Then you can subtract one date from another, divide the number of days by 7 and add 1 (to make it inclusive).
Personally I'd use Noda Time for all of this, but using DateTime:
// Always uses Monday-to-Sunday weeks
public static DateTime GetStartOfWeek(DateTime input)
{
// Using +6 here leaves Monday as 0, Tuesday as 1 etc.
int dayOfWeek = (((int) input.DayOfWeek) + 6) % 7;
return input.Date.AddDays(-dayOfWeek);
}
public static int GetWeeks(DateTime start, DateTime end)
{
start = GetStartOfWeek(start);
end = GetStartOfWeek(end);
int days = (int) (end - start).TotalDays;
return (days / 7) + 1; // Adding 1 to be inclusive
}
Complete example:
using System;
class Program
{
static void Main (string[] args)
{
ShowWeeks(new DateTime(2016, 9, 17), new DateTime(2016, 9, 26));
ShowWeeks(new DateTime(2016, 9, 17), new DateTime(2016, 9, 25));
ShowWeeks(new DateTime(2016, 9, 19), new DateTime(2016, 9, 26));
ShowWeeks(new DateTime(2016, 9, 12), new DateTime(2016, 9, 25));
}
static void ShowWeeks(DateTime start, DateTime end)
{
int weeks = GetWeeks(start, end);
Console.WriteLine($"{start:d} {end:d} {weeks}");
}
// Always uses Monday-to-Sunday weeks
public static DateTime GetStartOfWeek(DateTime input)
{
// Using +6 here leaves Monday as 0, Tuesday as 1 etc.
int dayOfWeek = (((int) input.DayOfWeek) + 6) % 7;
return input.Date.AddDays(-dayOfWeek);
}
public static int GetWeeks(DateTime start, DateTime end)
{
start = GetStartOfWeek(start);
end = GetStartOfWeek(end);
int days = (int) (end - start).TotalDays;
return (days / 7) + 1; // Adding 1 to be inclusive
}
}
Output (in my UK locale):
17/09/2016 26/09/2016 3
17/09/2016 25/09/2016 2
19/09/2016 26/09/2016 2
12/09/2016 25/09/2016 2

A bit "simplified", because the Monday is needed just for the start date:
static int weeks(DateTime d1, DateTime d2) {
var daysSinceMonday = ((int)d1.DayOfWeek + 6) % 7;
return ((d2 - d1).Days + daysSinceMonday) / 7 + 1;
}

See my method below, I "strechted" the weeks to monday untill sunday, and then calculated the total days / 7
public static void Main(string[] args)
{
Console.WriteLine(CalculateWeeks(new DateTime(2016, 9, 17), new DateTime(2016, 9, 26)));
Console.WriteLine(CalculateWeeks(new DateTime(2016, 9, 17), new DateTime(2016, 9, 25)));
Console.WriteLine(CalculateWeeks(new DateTime(2016, 9, 19), new DateTime(2016, 9, 26)));
Console.WriteLine(CalculateWeeks(new DateTime(2016, 9, 12), new DateTime(2016, 9, 25)));
}
public static double CalculateWeeks(DateTime from, DateTime to)
{
if (to.DayOfWeek != DayOfWeek.Sunday)
to = to.Add(new TimeSpan(7- (int) to.DayOfWeek, 0, 0, 0)).Date;
return Math.Ceiling((to - from.Subtract(new TimeSpan((int)from.DayOfWeek - 1, 0, 0, 0)).Date).TotalDays / 7);
}

Get total hours that fall between a specific time period

the condition is Time in and Time out (e.g 02/01/2015 02:55 'til 02/02/2015 05:55) that is more than a day. I already computed the total hours of Time in and Time out, and I want to know if the total hours has passed between 23:00(11:00PM ) up to 06:00AM and get the total of it

var hours = (datevalue1 - datevalue2).TotalHours;
or
Timespace ts= (datevalue1 - datevalue2);
var hours = ts.Value.TotalHours;

Try this way.. DateTime.Parse().Subtract()
eg:
string startTime = "11:00 PM";
string endTime = "6:00 AM";
TimeSpan duration = DateTime.Parse(endTime).Subtract(DateTime.Parse(startTime));
Console.WriteLine(duration);
Console.ReadKey();
OR
TimeSpan is the object you need:
TimeSpan span = (DateTime.Now - DateTime.Now);
String.Format("{0} days, {1} hours, {2} minutes, {3} seconds",
span.Days, span.Hours, span.Minutes, span.Seconds);

You can calculate it by passing over time. when its night time add it to TimeSpan.
DateTime timeIn = new DateTime(2015, 09, 29, 10, 11, 3); // 29-09-2015 at 10:11:03
DateTime timeOut = new DateTime(2015, 10, 1, 2, 19, 18); // 01-10-2015 at 02:19:38
TimeSpan nightTime = new TimeSpan(); //total amount of night time
TimeSpan passLength = new TimeSpan(0, 0, 0, 1); // length of time to pass at each iteration (1s)
while (timeIn < timeOut) // do it until timeIn reaches timeOut
{
timeIn = timeIn.Add(passLength); // add 1 second to timeIn
if (timeIn.Hour < 6 || timeIn.Hour == 23) // if we are in range of night time
{
nightTime = nightTime.Add(passLength); // add 1 second to night time
}
}
Console.WriteLine(nightTime);
You can do lot of optimizations. for long times its not good idea to add 1 sec each time. you can add 1 day to TimeIn at each iterate then add only 6 hours to night time. after you get close to Timeout decrease length time
Here is a better way. first get days fast. then get rest of the time.
DateTime timeIn = new DateTime(2015, 09, 29, 10, 11, 3); // 29-09-2015 at 10:11:03
DateTime timeOut = new DateTime(2015, 10, 1, 2, 19, 18); // 01-10-2015 at 02:19:38
// Get days
TimeSpan passLength = new TimeSpan(1, 0, 0, 0); // one day per iterate
while (timeIn + passLength < timeOut)
{
timeIn = timeIn.Add(passLength);
nightTime = nightTime.Add(new TimeSpan(0, 7, 0, 0)); // 7 hours of a day passed is considered night time
}
// Get rest of the time
passLength = new TimeSpan(0, 0, 0, 1); // one second per iterate
while (timeIn < timeOut) // do it until timeIn reaches timeOut
{
timeIn = timeIn.Add(passLength); // add 1 second to timeIn
if (timeIn.Hour < 6 || timeIn.Hour == 23) // if we are in range of night time
{
nightTime = nightTime.Add(passLength); // add 1 second to night time
}
}
Console.WriteLine(nightTime);
You shouldn't be worry about rest of the time calculation performance. since the rest of the time is now less than 1 day which is only 86400 seconds.
Less than 86400 iterates should be fine for today's processors speed. how ever you can still optimize it farther away but you don't get much more performance.

A little bit different and faster approach:
static void Main(string[] args)
{
TimeSpan result = new TimeSpan();
DateTime dt1 = new DateTime(2015, 09, 29, 10, 11, 03);
DateTime dt2 = new DateTime(2015, 10, 01, 02, 19, 38);
DateTime d1 = new DateTime(dt1.Year, dt1.Month, dt1.Day, 0, 0, 0); //Date only
DateTime d2 = new DateTime(dt2.Year, dt2.Month, dt2.Day, 0, 0, 0); //Date only
//Count night time in first day
result += DateTime.Compare(dt1, d1.AddHours(6)) > 0 ? new TimeSpan(6, 0, 0) : new TimeSpan(dt1.Hour, dt1.Minute, dt1.Second);
if (DateTime.Compare(dt1, d1.AddHours(23)) > 0) result += new TimeSpan(dt1.Hour - 23, dt1.Minute, dt1.Second);
//Count night time in last day
result += DateTime.Compare(dt2, d2.AddHours(6)) > 0 ? new TimeSpan(6, 0, 0) : new TimeSpan(dt2.Hour, dt2.Minute, dt2.Second);
if (DateTime.Compare(dt2, d2.AddHours(23)) > 0) result += new TimeSpan(dt1.Hour - 23, dt2.Minute, dt2.Second);
//Count night time in middle days
int daysBetween = (int)(d2 - d1).TotalDays - 1;
result += new TimeSpan(daysBetween * 7, 0, 0);
Console.WriteLine("Night time: " + result);
Console.ReadKey();
}

Compare EndTime with your Range(23:00-06:00)
that is in your Case, check wether EndTime 05:55 < 06:00 and EndTime 05:55 > 23:00

You can subtract the DateTime values to get the TimeSpan in between. Then you can get the TotalHours in that
var hours = timeOut.Subtract(timeIn).TotalHours;
For example
timeIn = 29-09-2015 10:11:03;
timeOut = 01-10-2015 02:19:38;
hours = 52.14303137125;