Develop Reference

How to check if between two points in time C#

I'm setting up a scheduling system for one of my projects and one thing in particular that I need to do is allow for multiple windows to be present within each day. A window would represent two points in time, the start and the end.
I am not sure just how I should approach this issue. I can do this in a very hacky way but I would rather know how to do it right, so that I can be satisfied that my code is as it should be.
What I'm currently attempting to do is as seen here:
public class ScheduleWindow
{
public string Name;
public DateTime EndTime;
public DateTime StartTime;
}
I have a name id for my schedule, but for this that is irrelevant.
I have a date in time at which the window will start.
I have a date in time at which the window will end.
The intent for the following method is to add a window to a schedule. I want the schedule to represent my day, so I'm using the current year, month and day and then setting the hours and minutes to the points in time that I would like this window to be active.
public void AddWindow(string name, int startHour, int endHour, int startMinute, int endMinute)
{
var year = DateTime.Now.Year;
var month = DateTime.Now.Month;
var day = DateTime.Now.Day;
var startTime = new DateTime(year: year, month: month, day: day, hour: startHour, minute: startMinute, second: 0, millisecond: 0);
var endTime = new DateTime(year: year, month: month, day: day, hour: endHour, minute: endMinute, second: 0, millisecond: 0);
var window = new ScheduleWindow()
{
EndTime = endTime,
StartTime = startTime,
Name = name
};
_scheduleWindows.Add(window);
}
So now we're to the root of my issue.
I am actually completely unsure of how to check if we are within that time window.
`public bool WindowIsActive()
{
foreach (var window in _scheduleWindows)
{
...
//if any window is currently active, return true
}
}`
I've been fiddling here with this code for some time now, and any help would be super appreciated. If anyone can give me some pointers to perhaps a solution that would work better, that would be awesome!
The goal is to check and see if any window is currently active. Currently, I have no clue how.

I imagine it's look something like this
public bool WindowIsActive()
{
foreach (var window in _scheduleWindows)
{
if (DateTime.Now >= window.StartTime && DateTime.Now <= window.EndTime)
{
return true;
}
}
}
This works because DateTime implements the GreaterThanOrEqual and LessThanOrEqual operators.
Two things to consider about this answer:
This code assumes EndTime is later than StartTime.
If you care about timezones, you should use DateTimeOffset instead.

You can use < and > operators to compare DateTimes.
[edit: I realized that you just wanted to compare the time of day - i.e. disregarding the month and year - you'd use the TimeOfDay property of DateTime]
var timeOfDay = DateTime.Now.TimeOfDay; //this is a TimeSpan type
if(timeOfDay > window.StartTime.TimeOfDay && timeOfDay < window.EndTime.TimeOfDay)
{
//time is within the time window.
}

Define a Custom Weekend Starting and Ending Day & Time and finding its occurrences over date range

I am having a tough time in calculating the number of custom defined weekends and later finding them over a specified date range, I have to apply different rates based on the days (weekends, season days & normal days).
For example, a trip is starting at 16/08/2017 09:00:00 and ending at 29/08/2017 09:00:00 where as my weekend start at Fri 15:00:00 till Mon 09:00:00 every week. I need to calculate how many weekends occur in the given trip start and end time and how many regular days, as both are charged at different rates. Any help is appreciated.
Please note that all the date and times will be dynamic and can be changed, so looking for a generic solution

If your range is small enough you can try:
public class DateTimeRange
{
private DateTime Start { get; set; }
private DateTime End { get; set; }
public DateTimeRange(DateTime start, DateTime end)
{
Start = start;
End = end;
}
public int DayOffsCount()
{
var current = Start;
var dayOffsCount = 0;
while (current < End)
{
if (IsDayOff(current))
{
dayOffsCount++;
}
current = current.AddDays(1);
}
return dayOffsCount;
}
}
public bool IsDayOff(DateTime dt)
{
if (dt.DayOfWeek == DayOfWeek.Saturday || dt.DayOfWeek == DayOfWeek.Sunday)
return true;
return IsHoliday(dt);
}

Get Date of every alternate Friday

I am wondering if i can get the date of every alternate friday starting with 13th of April, 2012 to give it as a parameter to a stored procedure using c#, asp.net?
It should also be most recently passed date. Thank you!

Just set a DateTime with the date you want to start at, and then keep adding 14 days:
So to get every other Friday after 4/13 until the end of the year:
DateTime dt = new DateTime(2012, 04, 13);
while (dt.Year == 2012)
{
Console.WriteLine(dt.ToString());
dt = dt.AddDays(14);
}
More info after comment:
If you want the most recent alternate Friday since 2012/04/13, you can compute the number of days between now and 2012/04/13, take the remainder of that divided by 14, and subtract that many days from today's date:
DateTime baseDate = new DateTime(2012, 04, 13);
DateTime today = DateTime.Today;
int days = (int)(today - baseDate).TotalDays;
int rem = days % 14;
DateTime mostRecentAlternateFriday = today.AddDays(-rem);

You can easily make a generator method that would give you the set of fridays:
public IEnumerable<DateTime> GetAlternatingFridaysStartingFrom(DateTime startDate)
{
DateTime tempDate = new DateTime(startDate.year, startDate.Month, startDate.Day);
if(tempDate.DayOfWeek != DayOfWeek.Friday)
{
// Math may be off, do some testing
tempDate = tempDate.AddDays((7 - ((int)DayOfWeek.Friday - (int)tempDate.DayOfWeek) % 7);
}
while(true)
{
yield return tempDate;
tempDate = tempDate.AddDays(14);
}
}
Then, simply use some LINQ to determine how much you want:
var numberOfFridays = GetAlternatingFridaysStartingFrom(DateTime.Today).Take(10);

Why do you need a stored proc?
If you have a date that is Friday, why not just use AddDays(14) in a loop?
If you want to find the nearest Friday from a start date, just use this:
while(date.DayOfWeek != DayOfWeek.Friday)
{
date.AddDays(1);
}
Then use the 14 day loop to get every other Friday.

You can create simple method that will enumerate them like so:
public static IEnumerable<DateTime> GetAlternatingWeekDay(DateTime startingDate)
{
for (int i = 1; ; i++)
{
yield return startingDate.AddDays(14*i);
}
}
Which you can call like this:
DateTime startingDate = DateTime.Parse("2012-04-13");
foreach (var date in GetAlternatingWeekDay(startingDate).Take(10))
{
Console.WriteLine(date.ToString("R"));
}
Alternately, if you need to know the date for a given number of weeks out, you could use code like this:
DateTime date = DateTime.Parse("2012-04-13").AddDays(7 * numberOfWeeks);

Determine if a date is a "work day off"

At my work, we are on the 9/80 plan where we get every other Friday off. We've got a small program that shows a DevExpress.Scheduler control and I'd like to color our "Friday's off" a different color. What I need to know is how do I know if a date is one of our Friday's off? The Friday's off will always be every other week (in other words, we don't skip a week due to a holiday or something like that). I have the date of our First Friday off of the year, so I think I can use that somehow...I can also get the date from the scheduler as it's drawn so I have something to compare to.
DateTime dtFirstFridayOff = new DateTime(2011, 1, 1);
DateTime dtCellDate = Convert.ToDateTime(e.Cell.Value);
Now I'm a bit lost as to how to check if dtCellDate is a Friday off.

public static bool IsDateMultipleDays(DateTime originalDate, int numberOfDays, DateTime potentialDate)
{
var original = originalDate.Date; // to make sure that it doesn't have a time portion
var potential = potentialDate.Date;
var difference = potential - original;
return (int)difference.TotalDays % numberOfDays == 0;
}
Then you'd call it like this:
IsDateMultipleDays(dtFirstFridayOff, 14, dtCellDate)

Try this:
bool IsFridayOff(DateTime dt)
{
if (dt.DayOfWeek != DayOfWeek.Friday)
{
return false;
}
DateTime dtFirstFridayOff = new DateTime(2011, 1, 1);
TimeSpan span = dtFirstFridayOff - dt.Date;
return (int) span.TotalDays%14 == 0;
}

How to loop between two dates

I have a calendar which passes selected dates as strings into a method. Inside this method, I want to generate a list of all the dates starting from the selected start date and ending with the selected end date, obviously including all of the dates inbetween, regardless of how many days are inbetween the selected start and end dates.
Below I have the beginning of the method which takes the date strings and converts them into DateTime variables so that I can make use of the DateTime calculation functions. However, I cannot seem to work out how to calculate all of the dates inbetween the start and end date?
Obviously the first stage is to subtract the start date from the end date, but I cannot calculate the rest of the steps.
Help appreciated greatly,
kind regards.
public void DTCalculations()
{
List<string> calculatedDates = new List<string>();
string startDate = "2009-07-27";
string endDate = "2009-07-29";
//Convert to DateTime variables
DateTime start = DateTime.Parse(startDate);
DateTime end = DateTime.Parse(endDate);
//Calculate difference between start and end date.
TimeSpan difference = end.Subtract(start);
//Generate list of dates beginning at start date and ending at end date.
//ToDo:
}

static IEnumerable<DateTime> AllDatesBetween(DateTime start, DateTime end)
{
for(var day = start.Date; day <= end; day = day.AddDays(1))
yield return day;
}
Edit: Added code to solve your particular example and to demonstrate usage:
var calculatedDates =
new List<string>
(
AllDatesBetween
(
DateTime.Parse("2009-07-27"),
DateTime.Parse("2009-07-29")
).Select(d => d.ToString("yyyy-MM-dd"))
);

You just need to iterate from start to end, you can do this in a for loop
DateTime start = DateTime.Parse(startDate);
DateTime end = DateTime.Parse(endDate);
for(DateTime counter = start; counter <= end; counter = counter.AddDays(1))
{
calculatedDates.Add(counter);
}

The easiest thing to do would be take the start date, and add 1 day to it (using AddDays) until you reach the end date. Something like this:
DateTime calcDate = start.Date;
while (calcDate <= end)
{
calcDate = calcDate.AddDays(1);
calculatedDates.Add(calcDate.ToString());
}
Obviously, you would adjust the while conditional and the position of the AddDays call depending on if you wanted to include the start and end dates in the collection or not.
[Edit: By the way, you should consider using TryParse() instead of Parse() in case the passed in strings don't convert to dates nicely]

for( DateTime i = start; i <= end; i = i.AddDays( 1 ) )
{
Console.WriteLine(i.ToShortDateString());
}

An alternative method
public static class MyExtensions
{
public static IEnumerable EachDay(this DateTime start, DateTime end)
{
// Remove time info from start date (we only care about day).
DateTime currentDay = new DateTime(start.Year, start.Month, start.Day);
while (currentDay <= end)
{
yield return currentDay;
currentDay = currentDay.AddDays(1);
}
}
}
Now in the calling code you can do the following:
DateTime start = DateTime.Now;
DateTime end = start.AddDays(20);
foreach (var day in start.EachDay(end))
{
...
}
Another advantage to this approach is that it makes it trivial to add EachWeek, EachMonth etc. These will then all be accessible on DateTime.