Develop Reference

Check specific days exist in a set range of given weeks and add to list

What would be the best choice in getting and returning a list of specific dates between a 3 week range?
My intent is to create delivery dates based on a delivery centre's given days they are available
public List<DayOfWeek> DeliveryDays { get; set; }
DeliveryDays contains set values from 0-6 (0 being Sunday, 1 Monday, etc.)
I want to get those values, pass them through 3 weeks worth of following dates, and return those delivery days in a list (so only those centre's can order on select days).
Here's what I have so far:
public List<DateTime> CalculateAvailableDeliveryDates()
{
//Loop through 3 weeks of days
DateTime today = DateTime.Today; //Specify today's date
DateTime totalDateCount = today.AddDays(1); //Plus one day on each time counted
var dates = Enumerable.Range(0, 21).Select(days => totalDateCount.AddDays(days)).ToList(); //Count from 0 to 21 (3 weeks worth of days). On each count, run totalDateCount
//if exists in deliveryDayList
//add to dates via dates.Add func
if (DeliveryDays.Contains(DayOfWeek.Monday))
{
//action
} //and so on for each day
//return specific dates from date range
return dates;
}
currently I get a readout of 21 days. The if statement does nothing and is only serving as an example of my logic.
Would the best method be: rather than getting a list first, to do a check and nest if/case statements based on the DeliveryDates per centre and then return them into a list?
Thanks in advance.

Given a list of DayOfWeek, you can select all dates in the next 21 days that match one of those days of the week using System.Linq. The Enumerable.Range selects a range of numbers, Select will then select a bunch of DateTime objects representing Today plus some number of days, and Where is used to filter the results, comparing the DayOfWeek for each date to see if it exists in DeliveryDays:
List<DayOfWeek> DeliveryDays = new List<DayOfWeek>();
public List<DateTime> GetAvailableDeliveryDates()
{
// 1. Get a range of numbers representing the days to add
// to today, which will make up our range of dates
// 2. Select a date using Today.AddDays for each number
// 3. Filter on only days which are contained in DeliveryDays
return Enumerable.Range(0, 21) // Define the range
.Select(i => DateTime.Today.AddDays(i)) // Select the range
.Where(date => DeliveryDays.Contains(date.DayOfWeek)) // Filter the range
.ToList();
}

Comparing dates in C#

I am a beginning programmer in C# and asp.net. I am busy trying to create a Hotel application. Where somebody is able to book for example an 8 day vacation. But now I need to add a formula that calculates the price. The method I am writing is getting the price per night of the room from the database. And the days that the person is staying is entered in the view and passed down to the controller.So I want to calculate the price inside the controller. But now I have a problem cause the price of staying in the hotel is higher in the high-season than in the low-season. So the prices differs per day. But now I do not really now how to compare the dates so I am able to give an accurate total price.
I have looked over some threads on stack overflow and they often advice to use Timespan to compare dates. But I was wondering is Timespan the best solution for me? Cause for my project the price should flow and not be fixed. For example it should not be like 28 May - 10 July is €120 euro per night but more like 28 May €109, 29 May €112, 30 May €113 - 9 July €127, 10 July 130.
If I would succeed in creating a different price per day then the last thing should not be that hard I hope. The price of each date should be added to each other so I will have the total price.
So my questions are:
Is the best way to compare dates Timespan?
Is there an easy way to calculate this? I would not like fixed dates.
Are there any good tutorials for this?

I would just compare each Date object between the start and end dates to see if it falls within a defined range to determine the rate, and sum them as I go.
This is probably overkill for you, but I would encapsulate the different 'seasons' and their rates in a class, and add a method to the class that will determine if a date falls within that 'season'. This will simplify the other methods.
Then I would create a method that, given a single date, will return the rate for that date.
Finally, I would calculate the total price by calling the GetRate() method for each day between the client's start date (inclusive) and end date (exclusive).
Here's a sample of how I would do it. First, the class to hold a 'season'
public class Season
{
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
public int Rate { get; set; }
public bool ContainsDate(DateTime date)
{
// Assumption: Year is ignored - seasons are considered
// to start and end on the same date each year
//
// Rules: (remember a season may start in Dec and end in Jan,
// so you cant just check if the date is greater than
// the start or less than the end!)
//
// 1. If the start and end month are the same,
// return true if the month is equal to start (or end) month
// AND the day is between start and end days.
// 2. If the date is in the same month as the start month,
// return true if the day is greater than or equal to start day.
// 3. If the date is in the same month as the end month,
// return true if the day is less than or equal to end day.
// 4. If the StartMonth is less than the EndMonth,
// return true if the month is between them.
// 5. Otherwise, return true if month is NOT between them.
if (StartDate.Month == EndDate.Month)
return date.Month == StartDate.Month &&
date.Day >= StartDate.Day &&
date.Day <= EndDate.Day;
if (date.Month == StartDate.Month)
return date.Day >= StartDate.Day;
if (date.Month == EndDate.Month)
return date.Day <= EndDate.Day;
if (StartDate.Month <= EndDate.Month)
return date.Month > StartDate.Month && date.Month < EndDate.Month;
return date.Month < EndDate.Month || date.Month > StartDate.Month;
}
}
Next, a method that will calculate the rate for a specific date:
public static int GetRate(DateTime date)
{
// Normally these 'seasons' and rates would not be hard coded here
const int offSeasonRate = 125;
var winterSeason = new Season
{
StartDate = DateTime.Parse("November 15"),
EndDate = DateTime.Parse("January 12"),
Rate = 150
};
var springSeason = new Season
{
StartDate = DateTime.Parse("May 20"),
EndDate = DateTime.Parse("June 15"),
Rate = 140
};
var summerSeason = new Season
{
StartDate = DateTime.Parse("July 10"),
EndDate = DateTime.Parse("August 31"),
Rate = 170
};
// Create a list of all the seasons
var seasons = new List<Season> {winterSeason, springSeason, summerSeason};
// Loop through all the seasons and see if this date is in one of them
foreach (var season in seasons)
{
if (season.ContainsDate(date))
{
// Note: depending on your implementation, Rate could be a multiplier
// in which case you would return (offSeasonRate * season.Rate);
return season.Rate;
}
}
// If we get this far, the date was not in a 'season'
return offSeasonRate;
}
Finally, here is the method that gets the total price for a date range:
var startDate = DateTime.Today;
var endDate = startDate.AddDays(2);
var price = 0;
// Sum the rates for each day between
// start date (inclusive) and end date (exclusive).
for (var curDate = startDate; curDate < endDate; curDate = curDate.AddDays(1))
{
price += GetRate(curDate);
}
Console.WriteLine("The total cost from {0} to {1} is: €{2}",
startDate, endDate, price);

How to calculate sum of amount for each 5 weeks before in linq?

I am having the amount field in income table in database, as well as the created date in same table. I need data like,
Week 1 => Sum(amount for week 1)
Week 2 => Sum(amount for week 2)
Week 3 => Sum(amount for week 3)
Week 4 => Sum(amount for week 4)
Week 5 => Sum(amount for week 5)
What should be my linq query. I am using entity framework.
Edited:
Say previous 4 week of current week + current week =5 weeks. here current week is the week of today's date. eg. today is 26'th Aug 2014 so current week is from 24'th Aug 2014 (Sunday) to 30'th Aug 2014 (Saturday).

You can use the methods in EntityFunctions to perform date and time arithmetic. So you should start by working out the start and end dates, then use TruncateTime if necessary to truncate your created date to a date (instead of date and time), and use DiffDays to work out "number of days since the start of the period". Then just divide by 7 to group...
DateTime today = DateTime.Today;
DateTime start = today.AddDays(-(int) today.DayOfWeek) // Sunday...
.AddDays(-28); // 4 weeks ago
DateTime end = start.AddDays(7 * 5);
var result = from entry in db.Entries
where entry.Created >= start && entry.Created < end
group entry.Amount by EntityFunctions.DiffDays(start,
EntityFunctions.TruncateTime(entry.Created)) / 7 into g
select new { Week = g.Key + 1, Sum = g.Sum() };
While I'd expect that to work, I haven't personally done any date/time work in EF myself. The general approach should be fine, it's just that you may need to tweak it. Also note that this won't give you any results for weeks that don't have any entries - it's probably easiest to do that outside EF.
EDIT: If the summing part isn't working, it's easy to do the summing locally instead:
var query = from entry in db.Entries
where entry.Created >= start && entry.Created < end
group entry.Amount by EntityFunctions.DiffDays(start,
EntityFunctions.TruncateTime(entry.Created)) / 7;
var result = query.AsEnumerable() // Execute the rest locally
.Select(g => new { Week = g.Key + 1, Sum = g.Sum() });

How to group dates by week?

I am writing an Excel exporter for a bespoke application I am creating, and I have a question about LINQ grouping in C#.
Basically, this new Excel exporter class is given two dates. The class then retrieves all consignments between this date range.
As part of this exporter, I need to be able to group the dates into weeks, and get the values for that week. So for example, if I'm given 07/12/2011 and 22/12/2011 (dd/MM/yyyy format), I need to group all consignments between them ranges into weeks (each week beginning with Sunday). The ideal result using the above dates would be
Week 1: (consignments between 04/12/2011 and 10/12/2011)
Week 2: (consignments between 11/12/2011 and 17/12/2011)
Week 3: (consignments between 18/11/2011 and 24/12/2011)
Any ideas?

The fundamental question here is how to project a DateTime instance into a week of year value. This can be done using by calling Calendar.GetWeekOfYear. So define the projection:
Func<DateTime, int> weekProjector =
d => CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(
d,
CalendarWeekRule.FirstFourDayWeek,
DayOfWeek.Sunday);
You can configure exactly how the "week number" is determined by tweaking the parameters in the method call. You can also decide to define the projection as e.g. an extension method if you prefer; this does not change the essence of the code. In any case, you are then ready to group by week:
var consignmentsByWeek = from con in consignments
group con by weekProjector(con.Date);
If you also want to constrain the output to consigments between two specific dates, just add an appropriate where clause; the grouping logic does not change.

Hesitant though I am to disagree with as esteemed an answerer I believe the accepted answer here is wrong, and this is not fundamentally a question of projecting to a week of year value.
GetWeekOfYear(), and the concept in general, is about assigning index values to weeks within a year according to some agreed standard. It is not suitable for placing dates into groups of seven adjacent days as I believe the questioner requires.
Not only will use of GetWeekOfYear() as proposed result in groups of fewer than seven days at the end of many years, but worse still, as the various standards supported by GetWeekOfYear() will often apportion the first days of a year to the last week of the previous year, and yet the GetWeekOfYear() result contains only the integer week index with no reference to associated year, grouping by new { Year = date.Year, weekProjector(date) } or date.Year + "-" + weekProjector(date) in the questioner's year would see January 1st 2011 grouped in with Christmas Day through to New Year's Eve twelve months later that same year.
So I would argue that the original question is fundamentally one of projecting not to a week of year value but to a week of all time value, "week beginning y/m/d" you might say, so grouping need only be done by the first day of the week, i.e. (assuming you're happy to default to Sunday) simply:
group by date.AddDays(-(int)date.DayOfWeek)

In addition to Jon's answer you can get the date of the first day in the week then group by that date.
To get the date of the first day in the week.
you can use this code:
public static class DateTimeExtensions
{
public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek)
{
int diff = dt.DayOfWeek - startOfWeek;
if (diff < 0)
{
diff += 7;
}
return dt.AddDays(-1 * diff).Date;
}
}
then you can group by the first date of the week like this:
var consignmentsByWeek = from con in consignments
group con by con.Datedate.StartOfWeek(DayOfWeek.Monday);

I tried like this (and it's working :) )
#foreach (var years in _dateRange.GroupBy(y => y.Year))
{
<p>#years.Key</p>
foreach (var months in years.GroupBy(m => m.Month))
{
<p>#CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName(months.Key)</p>
foreach (var weeks in months.GroupBy(w => w.AddDays(-(int)w.DayOfWeek)))
{
<p>#weeks.Key.ToString("dd-MMM-yy")</p>
}
}
}

I noticed that the OP has week 1, week 2, etc. in the ideal output. These are not the week of the year, but the "index" of the week being displayed based on the consignment dates. Building on some of the other answers already provided, here is my solution:
void DoExample()
{
//Load some sample data
var range = new List<DateTime>();
var curDate = DateTime.ParseExact("07/12/2011", "dd/MM/yyyy", System.Globalization.CultureInfo.InvariantCulture);
var maxDate = DateTime.ParseExact("22/12/2011", "dd/MM/yyyy", System.Globalization.CultureInfo.InvariantCulture);
while(curDate < maxDate)
{
range.Add(curDate);
curDate = curDate.AddDays(1);
}
//Run the method to get the consignments
var c = GetConsignments(range, DayOfWeek.Sunday);
//Output to match OP's "ideal" specs
foreach(var v in c)
{
Console.WriteLine($"Week {v.EntryIndex + 1} (number {v.WeekOfYear} in year): (consignments between {v.RangeStart:dd/MM/yyyy} and {v.RangeEnd:dd/MM/yyyy}). Actual date range is {v.RangeStart:dd/MM/yyyy}-{v.RangeEnd:dd/MM/yyyy} ({(v.FullWeek ? "Full" : "Partial")} week)");
}
//Most other answers place a lot of value on the week of the year, so this would include that.
// Also includes the actual date range contained in the set and whether all dates in that week are present
foreach (var v in c)
{
Console.WriteLine($"Week {v.EntryIndex + 1} (number {v.WeekOfYear} in year): (consignments between {v.RangeStart} and {v.RangeEnd})");
}
}
//Note that this lets us pass in what day of the week is the start.
// Not part of OP's requirements, but provides added flexibility
public List<ConsignmentRange> GetConsignments(IEnumerable<DateTime>consignments, DayOfWeek startOfWeek=DayOfWeek.Sunday)
{
return consignments
.OrderBy(v => v)
.GroupBy(v => v.AddDays(-(int)((7 - (int)startOfWeek) + (int)v.DayOfWeek) % 7))
.Select((v, idx) => new ConsignmentRange
{
//These are part of the OP's requirement
EntryIndex = idx,
RangeStart = v.Key, // part of requirement
RangeEnd = v.Key.AddDays(6), // part of requirement
//These are added as potentially useful
WeekOfYear = CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(
v.Key, CalendarWeekRule.FirstFourDayWeek, startOfWeek),
FirstDate = v.Min(),
LastDate = v.Max(),
FullWeek = (v.Distinct().Count() == 7)
}
)
.ToList();
}
We'll also need this class defined (or a subset of it depending on what data you want to include):
public class ConsignmentRange
{
public int EntryIndex;
public int WeekOfYear;
public bool FullWeek;
public DateTime FirstDate;
public DateTime LastDate;
public DateTime RangeStart;
public DateTime RangeEnd;
}

Get Date Range by week number c# [duplicate]

This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
In .net, knowing the week number how can I get the weekdays date?
Hello,
I've got a question for ya'll.
How do i get the date range of a given week number.
For example:
If I enter week 12 the output should be:
21-03-2011
22-03-2011
23-03-2011
24-03-2011
25-03-2011
26-03-2011
27-03-2011
I really hope you guys can help me out, i just cant find the awnser anywhere!
Thanks in advance.

Note
I appear to have missed bug. The current code have been updated as of 2012-01-30 to account for this fact and we now derive the daysOffset based on Tuesday which according to Mikael Svenson appears to solve the problem.
These ISO8601 week date calculations are a bit wonky, but this is how you do it:
DateTime jan1 = new DateTime(yyyy, 1, 1);
int daysOffset = DayOfWeek.Tuesday - jan1.DayOfWeek;
DateTime firstMonday = jan1.AddDays(daysOffset);
var cal = CultureInfo.CurrentCulture.Calendar;
int firstWeek = cal.GetWeekOfYear(jan1, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
var weekNum = ww;
if (firstWeek <= 1)
{
weekNum -= 1;
}
var result = firstMonday.AddDays(weekNum * 7 + d - 1);
return result;
Basically calculate a reference point, then add days, the hard stuff has to do with the fact that week 53 can sometimes occur in January and week 1 can sometimes occur in December. You need to adjust for that and this is one way to do that.
The above code calculates the date off a year (yyyy) and week number (ww) and day of week (d).

Find out which day of the week was the first January of the year (e.g. in 2011 it was Saturday)
Add the necessary count of days to become the next monday (2 days)
From this day on, add (Number of weeks - 1) * 7 days to get the first day of the week you are interested in
-Display this day plus the next days to get the whole week

Something like this should do the trick
DateTime d = new DateTime(someYear, 1, 1);
d.AddDays(numWeeks * 7);
for (int x = 0; x < 7; x++)
{
Console.WriteLine(d.ToShortDateString());
d.AddDays(1);
}