Develop Reference

How to handle an System.ArgumentOutOfRangeException when the last month is reached

The following code section is used to output the date. I always need the following month. However, a System.ArgumentOutOfRangeException is thrown from this code:
DateTime startOfMonth = new DateTime(startTime.Year, startTime.Month+1, 1);
When startTime has reached the 12th month. As I understand it, the year is not increased by +1, which ultimately leads to this exception. I've tried to catch the exception but with no success. How can I handle this exception and take the year into account?
public static List<string> GetMonthDays()
{
DateTime startTime = DateTime.Now;
DateTime startOfMonth = new DateTime(startTime.Year, startTime.Month+1, 1);
int daysInMonth = DateTime.DaysInMonth(startTime.Year, startTime.Month);
List<string> currentMonth = new List<string>();
//string[] currentMonth = new string[daysInMonth];
for (int i = 0; i < daysInMonth; ++i)
{
DateTime currentDate = startOfMonth.AddDays(i);
CultureInfo ci = new CultureInfo("de-DE");
currentMonth.Add(currentDate.ToString("dddd - dd.MM.yy", ci));
}
return currentMonth;
}

Change the following code ...
DateTime startOfMonth = new DateTime(startTime.Year, startTime.Month+1, 1);
To ...
DateTime startOfMonth = new DateTime(startTime.Year, startTime.Month, 1).AddMonths(1)

Get Current Week Number (C#)

I have been looking at Microsoft's documents and many stack overflow posts but none seem to answer my question. I want to know the simplest and easiest way to get an accurate week number for the current date in c#. I am pretty new to c# so please try and keep it simple. I have tried using:
int week = DateTime.Now.DayOfYear/7;
Console.WriteLine(week)
but on Monday (when I would like it to move onto the next week) it would show as the previous week.
Eg: If the date was 21/12/2020 it would say the current week is the 50th, which is 2 weeks off. Then on 22/12/2020 it would say it is the 51st week, which is 1 week off.
Please Help & Thanks in advance.

This is probably what you are looking for:
DateTime dt = new DateTime(2020, 12, 21);
Calendar cal = new CultureInfo("en-US").Calendar;
int week = cal.GetWeekOfYear(dt, CalendarWeekRule.FirstDay, DayOfWeek.Monday);
Console.WriteLine(week);
You can change the CalendarWeekRule parameter to change the definition of the first week of the year:
FirstDay means that first week of the year can have any length. For example if the first day of the year was Sunday, it will be counted as week and the following Monday will be counted as part of second week.
FirstFourDayWeek means that the first week will be counted only if it mainly in this year. For example if the first day of the year will be Thursday the week will be counted, but if the year starts with Friday, the first week won't be counted.
FirstFullWeek means that the first week that will be counted will be the first full week of the year.

I have looked at this as well when I was writing an application in LotusNotes. From what I have found, the first week of the year must contain a Thursday. If you assume that Sunday is the last day of the week, then the lowest date for Sunday has to be the 4th. With this is mind (and I am very new to C# and all the intricacies) I wrote this code which will give you the week number of any given date and also the number of weeks for this year and the previous. #
public class DateCalculations
{
private readonly DateTime _weekDate;
private DateTime ThisSunday => GetSundayDate(_weekDate);
private DateTime FirstDay_ThisYear => DateTime.Parse($"01/01/{ ThisSunday.Year }");
private DateTime FirstDay_LastYear => DateTime.Parse($"01/01/{ ThisSunday.Year - 1 }");
private DateTime FirstDay_NextYear => DateTime.Parse($"01/01/{ ThisSunday.Year + 1 }");
private DateTime FirstSunday_ThisYear => GetSundayDate_WeekOne(FirstDay_ThisYear);
private DateTime FirstSunday_LastYear => GetSundayDate_WeekOne(FirstDay_LastYear);
private DateTime FirstSunday_NextYear => GetSundayDate_WeekOne(FirstDay_NextYear);
public DateCalculations(string weekDate)
{
if (DateTime.TryParse(weekDate, out _weekDate))
{
return;
}
else
{
throw new Exception("Incorrect date has been supplied");
}
}
private bool IsDateInFirstWeek(DateTime suppliedDate)
{
var output = false;
// First week must contain a Thursday, so lowest Sunday date possible is the 4th
if (suppliedDate.Day >= 4)
{
output = true;
}
return output;
}
private DateTime GetSundayDate(DateTime suppliedDate)
{
var checkDay = suppliedDate;
//Check if the day of the supplied date is a Sunday
while (checkDay.DayOfWeek != DayOfWeek.Sunday)
{
checkDay = checkDay.AddDays(1);
}
return checkDay;
}
private DateTime GetSundayDate_WeekOne(DateTime suppliedDate)
{
var checkDay = GetSundayDate(suppliedDate);
if (IsDateInFirstWeek(checkDay) == false)
{
checkDay = checkDay.AddDays(7);
}
return checkDay;
}
public int WeekNumber()
{
var output = 0;
if (ThisSunday == FirstSunday_ThisYear)
{
output = 1;
}
else if(ThisSunday > FirstSunday_ThisYear)
{
TimeSpan daysBetween = ThisSunday - FirstSunday_ThisYear;
output = (daysBetween.Days/7) + 1;
}
else
{
TimeSpan daysBetween = ThisSunday - FirstSunday_LastYear;
output = (daysBetween.Days / 7) + 1;
}
return output;
}
public int TotalWeeksThisYear()
{
TimeSpan daysBetween = FirstSunday_NextYear - FirstSunday_ThisYear;
return (daysBetween.Days / 7);
}
public int TotalWeeksLastYear()
{
TimeSpan daysBetween = FirstSunday_ThisYear - FirstSunday_LastYear;
return (daysBetween.Days / 7);
}
}
My console was used to test
class Program
{
static void Main()
{
var test = new DateCalculations("2021-01-03");
var weekNumber = test.WeekNumber();
var totalWeeks = test.TotalWeeksThisYear();
var pastWeeks = test.TotalWeeksLastYear();
Console.ReadLine();
}
}
The date format can be any string representation of a date (English or American)
Hope this helps. It may need refactoring though :)

Built on top of this answer: by #bunny4
But not everyone is located in the US or might have to support several cultures.
Use this solution to support a cultural defined week rule and first-Day rule.. e.g. Denmark has "FirstFourDayWeek" rule for weeks and "Monday" as first day of the week.
//for now, take the the current executing thread's Culture
var cultureInfo = Thread.CurrentThread.CurrentCulture;
//let's pick a date
DateTime dt = new DateTime(2020, 12, 21);
DayOfWeek firstDay = cultureInfo.DateTimeFormat.FirstDayOfWeek;
CalendarWeekRule weekRule = cultureInfo.DateTimeFormat.CalendarWeekRule;
Calendar cal = cultureInfo.Calendar;
int week = cal.GetWeekOfYear(dt, weekRule, firstDay);

Sum all the Timespan per row in DataGridView

This is my front end, in my case, I would like to add all the total hours of time in and time out of all my rows in my datagridview. My datagridview fields are id, employee code, date, timein and timeout.
Here is my back end, in here I computed the the late, the total hours, the day difference and the night difference. Is it possible to display on my textboxes the total hours, the late, the day diff and night based on the data on my datagridview. Sorry for my english, clarify my questions with yours.
string timeIn = datagridAttendance.CurrentRow.Cells["timeIn"].Value.ToString();
string timeOut = datagridAttendance.CurrentRow.Cells["timeOut"].Value.ToString();
DateTime tIn = Convert.ToDateTime(timeIn);
DateTime tOut = Convert.ToDateTime(timeOut);
TimeSpan span = tOut - tIn;
txtTotalHours.Text = Convert.ToString(span);
DateTime start = Convert.ToDateTime(txtStart.Text);
txtMe.Text = tIn.ToShortTimeString();
DateTime inTime = Convert.ToDateTime(txtMe.Text);
if (inTime > start)
{
TimeSpan late = inTime - start;
txtLate.Text = Convert.ToString(late);
}
else
{
txtLate.Text = "Not Late";
}
TimeSpan passLength = new TimeSpan(0, 0, 0, 1);
TimeSpan nightTime = new TimeSpan();
while (tIn < tOut)
{
tIn = tIn.Add(passLength);
if (tIn.Hour < 6 || tIn.Hour == 23)
{
nightTime = nightTime.Add(passLength);
}
}
txtNightDif.Text = Convert.ToString(nightTime);
TimeSpan day = span - nightTime;
txtDayDif.Text = Convert.ToString(day);

Your code will look like below with the arrays timein[] timeout[] being the values in each row of DataGridView
DateTime[] timein = { DateTime.Parse("1:00"), DateTime.Parse("3:00"), DateTime.Parse("5:00"), DateTime.Parse("7:00") };
DateTime[] timeout = { DateTime.Parse("2:00"), DateTime.Parse("4:00"), DateTime.Parse("6:00"), DateTime.Parse("8:00") };
TimeSpan totalTime = new TimeSpan();
for (int i = 0; i < timein.Count(); i++)
{
totalTime += timeout[i] - timein[i];
}​

You can do this in your database, and then return the sum of timespans as a column. That would be better and far easier.

Get DateTime by Adding Minutes but consider working hours and weekends

Interesting issue I'm facing and I just can't come up with an algorim to calculate.
Basically, what I want is to calculate a DateTime based on DateTime.Now.AddMinutes() but the Adding of minutes should take into consideration Working Hours and weekends.
In other words, if the time is currently 16:50 and i add 20 minutes, the method should return a DateTime for tomorrow morning at 08:10 (if tomorrow is not a weekend day).
I've started with some logic, but it's not complete. Does anyone have a sample which can save me a few hours of coding? This is what i've got so far:
public DateTime CalculateSLAFromNow(int minutes)
{
DateTime now = DateTime.Now;
TimeSpan slatimeaddedon = CalculateToNextWeekDay(DateTime.Now);
TimeSpan finalMinutesAddedon = slatimeaddedon.Add(new TimeSpan(0, minutes, 0));
DateTime SLATime = DateTime.Now.AddMinutes(slatimeaddedon.TotalMinutes);
return SLATime;
}
private TimeSpan CalculateToNextWeekDay(DateTime dt)
{
//Calculate.
}

public static DateTime CalculateSLAFromNow(int minutes)
{
double days = (double)minutes / 540;
DateTime now = DateTime.Now;
DateTime later = now;
while (days >= 1)
{
later = later.AddDays(1);
if (later.DayOfWeek == DayOfWeek.Saturday)
{
later = later.AddDays(2);
}
days--;
}
days = days * 540;
later = later.AddMinutes(days);
if (later.Hour > 17)
{
later = later.AddHours(15);
}
if (later.DayOfWeek == DayOfWeek.Saturday)
{
later = later.AddDays(2);
}
else if(later.DayOfWeek == DayOfWeek.Sunday)
{
later = later.AddDays(1);
}
return later;
}
There now it accounts for any number of minutes added (not the prettiest code, but it works)

Ok. Friend of mine wrote the following which works 100%. Thanks J for this. Herewith the complete solution:
private static DateTime DoCalculation(DateTime startDate, int minutes)
{
if (startDate.DayOfWeek == DayOfWeek.Sunday)
{
// if the input date is a sunday, set the actual SLA start date to the following monday morning 7:00AM
startDate = startDate.AddHours(24);
startDate = new DateTime(startDate.Year, startDate.Month, startDate.Day, 7, 0, 0);
}
else if (startDate.DayOfWeek == DayOfWeek.Saturday)
{
// if the input date is a saturday, set the actual SLA start date to the following monday morning 7:00AM
startDate = startDate.AddHours(48);
startDate = new DateTime(startDate.Year, startDate.Month, startDate.Day, 7, 0, 0);
}
DateTime resultDate = startDate;
for (int i = 0; i < minutes; i++)
{
resultDate = resultDate.AddMinutes(1);
// it is 5PM and time to go home
if (resultDate.Hour >= 17)
{
// if tomorrow is saturday
if (resultDate.AddDays(1).DayOfWeek == DayOfWeek.Saturday)
{
//add 48 hours to get us through the whole weekend
resultDate = resultDate.AddHours(48);
}
// add 14 hours to get us to next morning
resultDate = resultDate.AddHours(14);
}
}
return resultDate;
}

Ignore milliseconds when comparing two datetimes

I am comparing the LastWriteTime of two files, however it is always failing because the file I downloaded off the net always has milliseconds set at 0, and my original file has an actual value. Is there a simple way to ignore the milliseconds when comparing?
Here's my function:
//compare file's dates
public bool CompareByModifiedDate(string strOrigFile, string strDownloadedFile)
{
DateTime dtOrig = File.GetLastWriteTime(strOrigFile);
DateTime dtNew = File.GetLastWriteTime(strDownloadedFile);
if (dtOrig == dtNew)
return true;
else
return false;
}

I recommend you use an extension method:
public static DateTime TrimMilliseconds(this DateTime dt)
{
return new DateTime(dt.Year, dt.Month, dt.Day, dt.Hour, dt.Minute, dt.Second, 0, dt.Kind);
}
then its just:
if (dtOrig.TrimMilliseconds() == dtNew.TrimMilliseconds())

Care should be taken, if dt has non-zero microseconds (fractions of millis). Setting only milliseconds to zero is not enough.
To set millis and below to zero (and get a succesfull comparison), the code would be:
dt = dt.AddTicks(-dt.Ticks % TimeSpan.TicksPerSecond); // TimeSpan.TicksPerSecond=10000000

Create a new DateTime value with the milliseconds component set to 0:
dt = dt.AddMilliseconds(-dt.Millisecond);

TimeSpan difference = dtNew - dtOrig;
if (difference >= TimeSpan.FromSeconds(1))
{
...
}

You can subtract them, to get a TimeSpan.
Then use TimeSpan.totalSeconds()

This is overkill for a single Truncate, but if you have several and of various types you could do this using the generalized Extension Method below:
DateTime dtSecs = DateTime.Now.TruncateTo(Extensions.DateTruncate.Second);
DateTime dtHrs = DateTime.Now.TruncateTo(Extensions.DateTruncate.Hour);
More general Use Extension method:
public static DateTime TruncateTo(this DateTime dt, DateTruncate TruncateTo)
{
if (TruncateTo == DateTruncate.Year)
return new DateTime(dt.Year, 0, 0);
else if (TruncateTo == DateTruncate.Month)
return new DateTime(dt.Year, dt.Month, 0);
else if (TruncateTo == DateTruncate.Day)
return new DateTime(dt.Year, dt.Month, dt.Day);
else if (TruncateTo == DateTruncate.Hour)
return new DateTime(dt.Year, dt.Month, dt.Day, dt.Hour, 0, 0);
else if (TruncateTo == DateTruncate.Minute)
return new DateTime(dt.Year, dt.Month, dt.Day, dt.Hour, dt.Minute, 0);
else
return new DateTime(dt.Year, dt.Month, dt.Day, dt.Hour, dt.Minute, dt.Second);
}
public enum DateTruncate
{
Year,
Month,
Day,
Hour,
Minute,
Second
}

Here is the simplest way of doing this. You can control precision as you want.
bool AreEqual(DateTime a, DateTime b, TimeSpan precision)
{
return Math.Abs((a - b).TotalMilliseconds) < precision.TotalMilliseconds;
}
and usage is pretty self-explanatory
var _ = AreEqual(a, b, precision: TimeSpan.FromSeconds(1));

One way would be to create new dates, inputting the year, month, day, hour, minute, second into the constructor. Alternatively, you could simply compare each value separately.

Ether set the milliseconds in your other datetime to zero, or subtract one date from the other and just check the TotalMinutes property of the resulting time span.

instead of trimming unrelevant DateTime parts via creating new DateTimes, compare only relevant parts:
public static class Extensions
{
public static bool CompareWith(this DateTime dt1, DateTime dt2)
{
return
dt1.Second == dt2.Second && // 1 of 60 match chance
dt1.Minute == dt2.Minute && // 1 of 60 chance
dt1.Day == dt2.Day && // 1 of 28-31 chance
dt1.Hour == dt2.Hour && // 1 of 24 chance
dt1.Month == dt2.Month && // 1 of 12 chance
dt1.Year == dt2.Year; // depends on dataset
}
}
I took answer by Dean Chalk as base for performance comparison, and results are:
CompareWith is a bit faster than TrimMilliseconds in case of equal dates
CompareWith is a faster than dates are not equal
my perf test (run in Console project)
static void Main(string[] args)
{
var dtOrig = new DateTime(2018, 03, 1, 10, 10, 10);
var dtNew = dtOrig.AddMilliseconds(100);
//// perf run for not-equal dates comparison
//dtNew = dtNew.AddDays(1);
//dtNew = dtNew.AddMinutes(1);
int N = 1000000;
bool isEqual = false;
var sw = Stopwatch.StartNew();
for (int i = 0; i < N; i++)
{
// TrimMilliseconds comes from
// https://stackoverflow.com/a/7029046/1506454
// answer by Dean Chalk
isEqual = dtOrig.TrimMilliseconds() == dtNew.TrimMilliseconds();
}
var ms = sw.ElapsedMilliseconds;
Console.WriteLine("DateTime trim: " + ms + " ms");
sw = Stopwatch.StartNew();
for (int i = 0; i < N; i++)
{
isEqual = dtOrig.CompareWith(dtNew);
}
ms = sw.ElapsedMilliseconds;
Console.WriteLine("DateTime partial compare: " + ms + " ms");
Console.ReadKey();
}

You could create an extension method that would set the milliseconds to zero for a DateTime object
public static DateTime ZeroMilliseconds(this DateTime value) {
return new DateTime(value.Year, value.Month, value.Day,
value.Hours, value.Minutes, value.Seconds);
}
Then in your function
if (dtOrig.ZeroMilliseconds() == dtNew.ZeroMilliseconds())
return true;
else
return false;

Simply you can use datetime format with the format you want, and convert it again to datetime as below,
//compare file's dates
String format1 = #"yyyy-MM-dd HH:mm:ss"; // you also can avoid seconds if you want
public bool CompareByModifiedDate(string strOrigFile, string strDownloadedFile)
{
//.here we will use the format
DateTime dtOrig = Convert.ToDateTime(File.GetLastWriteTime(strOrigFile).ToString(format1));
DateTime dtNew = Convert.ToDateTime(File.GetLastWriteTime(strDownloadedFile).ToString(format1));
if (dtOrig == dtNew)
return true;
else
return false;
}

cast sortable strings and compare. simple and run well.
return string.Compare(dtOrig.ToString("s"), dtNew.ToString("s"),
StringComparison.Ordinal) == 0;

The most straightforward way to truncate time is to format it and parse on the units that you want:
var myDate = DateTime.Parse(DateTime.Now.ToString("MM/dd/yyyy hh:mm:ss"));
DOK's method re-written
public bool CompareByModifiedDate(string strOrigFile, string strDownloadedFile)
{
DateTime dtOrig = DateTime.Parse(File.GetLastWriteTime(strOrigFile).ToString("MM/dd/yyyy hh:mm:ss"));
DateTime dtNew = DateTime.Parse(File.GetLastWriteTime(strDownloadedFile).ToString("MM/dd/yyyy hh:mm:ss"));
if (dtOrig == dtNew)
return true;
else
return false;
}

Don't know why almost all programmers needs extra lines to return a bool value from a function with a bool expression.
instead
if (dtOrig.ZeroMilliseconds() == dtNew.ZeroMilliseconds())
return true;
else
return false;
you can always just use
return dtOrig.ZeroMilliseconds() == dtNew.ZeroMilliseconds()
if the expression is true it returns true else false.