We Keep Coding

Calculating no of weekends in between the two given date and time fields by considering the time difference and output the difference in minutes

I have two fields startdate and enddate. I need to calculate how many weekends in between two date and time fields and show the result in minutes.
For example start date is 01/11/2019 00:00:00 and end date as 03/11/2019 11:00:00. Below code is returning the difference in minutes correctly as 2100 minutes but when I keep the dates as02/11/2019 08:00 and 03/11/2019 00:00 I am getting the result as 1440 but my expected result is 960 minutes.
I understand that's because I am adding 1440 in code so how to correct this?
public double CountOfWeekEnds(DateTime startDate, DateTime endDate)
{
double weekEndCount = 0;
if (startDate > endDate)
{
DateTime temp = startDate;
startDate = endDate;
endDate = temp;
}
TimeSpan diff = endDate - startDate;
int days = diff.Days;
for (var i = 0; i <= days; i++)
{
var testDate = startDate.AddDays(i);
if (testDate.DayOfWeek == DayOfWeek.Saturday || testDate.DayOfWeek == DayOfWeek.Sunday)
{
if (testDate.Date < endDate.Date)
{
weekEndCount += 1440; // 24h * 60 min
}
else
{
var todayStart = new DateTime(testDate.Year, testDate.Month, testDate.Day, 0, 0, 0);
var difference = (endDate - todayStart).TotalMinutes;
weekEndCount += difference;
}
}
}
return weekEndCount;
}

OK, i simplified what i said a little down to:
DateTime start = new DateTime(2019,11,1,0,0,0);
DateTime end = new DateTime(2019, 11, 3, 11, 0, 0);
TimeSpan diff = end - start;
Console.WriteLine(diff.TotalDays);
int total = 0;
for (int i = 0; i<Math.Ceiling(diff.TotalDays); i++)
{
DateTime test = start.AddDays(i);
Console.WriteLine(test.DayOfWeek);
if (test.DayOfWeek == DayOfWeek.Saturday || test.DayOfWeek == DayOfWeek.Sunday)
{
if (test.Date==start.Date)
{
Console.WriteLine("start");
total += (23 - start.Hour) * 60 + (60 - start.Minute);
}
else if (test.Date==end.Date)
{
Console.WriteLine("end");
total += end.Hour * 60 + end.Minute;
}
else
{
total += 24 * 60;
}
}
Console.WriteLine(test + " total " + total);
}
Console.WriteLine("done");
Console.WriteLine(total);
which counts all saturdays and sundays and allows for start and ends to be partials
(and can someone send a keyboard with actual keys this membrain lark is hampering typings)

Trying to remain as much of the original code as possible, only three minor changes have to be made:
1. Use the actual dates to calculate diff:
TimeSpan diff = endDate.Date - startDate.Date; instead of TimeSpan diff = endDate - startDate;
This is because later in the upcoming for-loop you are trying to evaluate each date in order to say if is a saturday or sunday. Otherwise, you are evaluating if the date 24 (, 48, …) hours after your starting time stamp is a saturday or sunday.
2. Use testDate instead of todayStart in order to calculate difference
difference = (endDate - testDate).TotalMinutes;
instead of
var todayStart = new DateTime(testDate.Year, testDate.Month, testDate.Day, 0, 0, 0);
var difference = (endDate - todayStart).TotalMinutes;
This is because testDate does contain the hours and minutes to calculate the difference in minutes. Otherwise you are just ignoring the day time of the starting day. Note that this correction can lead to a negative difference value if the startDate day time is later than the endDate day time.
3. do not add a whole day if there is only one day to examine in total
That means that if startDate.Date == endDate.Date, you should just calculate the difference between the dates.
if (testDate.Date < endDate.Date && startDate.Date != endDate.Date)
This has to be done because of the code logic: a full day is added for every new day other than the final day and for the final day ~24hours are added or substracted to the final value depending on the day times of the startDate and endDate.
The complete corrected code:
public static double CountOfWeekEnds(DateTime startDate, DateTime endDate)
{
double weekEndCount = 0;
if (startDate > endDate)
{
DateTime temp = startDate;
startDate = endDate;
endDate = temp;
}
TimeSpan diff = endDate.Date - startDate.Date; //instead of endDate - startDate
int days = diff.Days;
for (var i = 0; i <= days; i++)
{
var testDate = startDate.AddDays(i);
//Console.WriteLine(testDate);
if (testDate.DayOfWeek == DayOfWeek.Saturday || testDate.DayOfWeek == DayOfWeek.Sunday) //only weekends count
{
if (testDate.Date < endDate.Date && startDate.Date != endDate.Date) { // added startDate.Date != endDate.Date
weekEndCount += 1440; // 24h * 60 min
//Console.WriteLine("************************add 1440 ");
}
else
{
double difference;
difference = (endDate - testDate).TotalMinutes; //instead of endDate - todayStart
//Console.WriteLine("************************add " + difference);
weekEndCount += difference;
}
}
}
//return days;
return weekEndCount;
}

You need to have a look at this condition:
if (testDate.Date < endDate.Date)
It means that "as long as the ticks of testDate is less than the ticks of endDate".
This condition will be true for all conditions that makes your variable "days" positive.
I think you need to extend this, condition e.g.
if ((endDate - todayStart).TotalMinutes > 1440 )
This way it will check whether it is AT LEAST 24 hours earlier. If it isn't it should go forth with your "else" condition and take the used fraction of the start day into consideration.

Here is a (somewhat) simple solution. Please note that the code could (and probably should) be refactored if it was to be production code. But I tried to optimize it for understandability, since it was your first post...
public static int CalculateWeekendMinutes(DateTime start, DateTime end)
{
int weekendMinutes = 0;
// First and last day will be handled seperately in the end
var firstFullDay = start.AddDays(1).Date;
var lastFullDay = end.AddDays(-1).Date;
TimeSpan limitedSpan = lastFullDay - firstFullDay;
int spanLengthDays = (int)limitedSpan.TotalDays;
var dateIterator = firstFullDay;
// Looping over the limited span allows us to analyse all the full days
while (dateIterator <= lastFullDay)
{
if (dateIterator.DayOfWeek == DayOfWeek.Saturday || dateIterator.DayOfWeek == DayOfWeek.Sunday)
{
weekendMinutes += (24 * 60);
}
dateIterator = dateIterator.AddDays(1);
}
// Finally we can calculate the partial days and add that to our total
weekendMinutes += CalculateMinutesOnFirstDay(start);
weekendMinutes += CalculateMinutesOnLastDay(end);
return weekendMinutes;
}
// Helps us calculate the minutes of the first day in the span
private static int CalculateMinutesOnFirstDay(DateTime date)
{
if (date.DayOfWeek == DayOfWeek.Saturday || date.DayOfWeek == DayOfWeek.Sunday)
{
// We want to know how many minutes there are UNTIL the next midnight
int minutes = (int)(date.Date.AddDays(1) - date).TotalMinutes;
return minutes;
}
else
{
return 0;
}
}
// Helps us calculate the minutes of the last day in the span
private static int CalculateMinutesOnLastDay(DateTime date)
{
if (date.DayOfWeek == DayOfWeek.Saturday || date.DayOfWeek == DayOfWeek.Sunday)
{
// We want to know how many minutes there are SINCE the last midnight
int minutes = (int)(date - date.Date).TotalMinutes;
return minutes;
}
else
{
return 0;
}
}

Timespan difference not calculating correctly

I am building a web form in C#. I have 3 drops downs for Start Time (Start Hour, Start Minute, and Start Time of Day (AM or PM) and 3 for finish time. My goal is to calculate the difference. Everything works fine until I choose noon or midnight. When I choose noon and debug, the value shows as 1. Here is my code.
var startHourDDL = ddlStartHour.SelectedValue;
var startMinuteDDL = ddlStartMinute.SelectedValue;
var startTOD = ddlStartTOD.SelectedValue;
int startHour = Convert.ToInt32(startHourDDL);
int startMinute = Convert.ToInt32(startMinuteDDL);
var finishHourDDL = ddlFinishHour.SelectedValue;
var finishMinuteDDL = ddlFinishMinute.SelectedValue;
var finishTOD = ddlFinishTOD.SelectedValue;
int finishHour = Convert.ToInt32(finishHourDDL);
int finishMinute = Convert.ToInt32(finishMinuteDDL);
if (startTOD == "PM")
{
startTime = new TimeSpan(startHour + 12, startMinute, 0);
}
else
{
startTime = new TimeSpan(startHour, startMinute, 0);
}
if (finishTOD == "PM")
{
finishTime = new TimeSpan(finishHour + 12, finishMinute, 0);
}
else
{
finishTime = new TimeSpan(finishHour, finishMinute, 0);
}
TimeSpan diff = finishTime - startTime;
string time = String.Format(diff.Hours + " Hours, " + diff.Minutes + " Minutes");
lblDurAmount.Text = time;
So if I choose 2:00 PM for start time and 4:00 PM for finish time, the label shows 2 hours. However, if I choose 12:00 PM for start time and 2:00 PM for finish time I get -10 hours.
This is what I get for start time when I debug at 12:00 PM.
{1.00:00:00}
Here is what I get when I choose 5:00 PM
{17:00:00}
I can't figure out why it won't set noon to 24. I even tried adding an if statement
if (startHour == 12 && startTOD)
{
startTime = new TimeSpan(24, startMinute, 0);
}
But that didn't work either. Value was still 1.00.

A TimeSpan is for storing a duration of time, not a time during the day.
As such, while you believe you are storing "12PM", what you are actually storing is a 24 hour time period. And "2PM" is a 14 hour time period.
Thus "2PM" - "12PM" = 14 hours - 24 hours (i.e. -10 hours).
To solve this, you need to store date/time in DateTime, not TimeSpan.

Your operations works only if the startTime is less than the finishTime otherwise all the results will come back as negatives. In your example 12 PM comes after 2 PM so when you subtract 2 PM - 12 PM you get then -10 hours.
You need to check if startTime is after finishTime and swap the two values if true
if (finishTime < startTime)
{
TimeSpan swap = finishTime;
finishTime = startTime;
startTime = swap;
}
TimeSpan diff = finishTime - startTime;
string time = String.Format(diff.TotalHours + " Hours, " + diff.Minutes + " Minutes");

Milliseconds to the highest possible time value before reaching 0,xx

I would like to write a converter from milliseconds to the highest possible time value before reaching a 0,x value.
Let me clarify this with examples.
Let's assume you have 1500ms this should result in 1,5secs, because its the highest possible digit value not resulting in 0,x.
So different examples would be
10ms = 10,0ms
100ms = 100,0ms
1000ms = 1,0sec
10000ms = 10,0sec
100000ms = 1,6min
1000000ms = 16,0min
10000000ms = 2,7hours
(The method should more or less be endless, so from hours to days, to weeks, to months, to years, to decades and so on...)
Is there a .net method for this?

Something like the following
public static string ConversionMethod(UInt64 ms)
{
// change output format as needed
string format = "######.###";
var cutoffs = new List<UInt64>() {
1000, // second
60000, // minute
3600000, // hour
86400000, // day
604800000, // week = day * 7
2592000000, // month = day * 30
31536000000, // year = day * 365
315360000000, // decade = year * 10
3153600000000, // century = decade * 10 (100 years)
31536000000000, // millenia = century * 10 (1000 years)
31536000000000000 // megayear = year * 100000
// 18446744073709551615 // UInt64 MaxValue
// 31536000000000000000 // gigayear = year * 100000000
};
var postfix = new List<String>() {
"second",
"minute",
"hour",
"day",
"week",
"month",
"year",
"decade",
"century",
"millenia",
"megayear"
};
// The above are listed from smallest to largest for easy reading,
// but the comparisons need to be made from largest to
// smallest (in the loop below)
cutoffs.Reverse();
postfix.Reverse();
int count = 0;
foreach (var cutoff in cutoffs)
{
if (ms > cutoff)
{
return ((decimal)((decimal)ms / (decimal)cutoff)).ToString(format) + " " + postfix[count];
}
count++;
}
return ms + " ms";
}
Conversion for the fraction is a bit dirty, might want to clean that up. Also, you'll have to decide how you want to handle leap years (and leap seconds), etc.

While not the final solution, maybe TimeSpan can help you achieve what you are looking for.
It is to be noted however, TimeSpan supports only up to TotalDays.
var timespan = TimeSpan.FromMilliseconds(1500);
var seconds = timespan.TotalSeconds; // equals: 1.5

It seems the TimeSpan class is the closest thing that meets your need, but clearly it's not exactly what you want. My take on it would look something like this:
public static string ScientificNotationTimespan(int milliseconds)
{
var timeSpan = new TimeSpan(0, 0, 0, 0, milliseconds);
var totalDays = timeSpan.TotalDays;
if (totalDays < 7)
{
if (timeSpan.TotalDays > 1) return timeSpan.TotalDays.ToString() + " days";
if (timeSpan.TotalHours > 1) return timeSpan.TotalHours.ToString() + " hours";
if (timeSpan.TotalMinutes > 1) return timeSpan.TotalMinutes.ToString() + " minutes";
if (timeSpan.TotalSeconds > 1) return timeSpan.TotalSeconds.ToString() + " seconds";
return milliseconds.ToString() + "milliseconds";
}
var weeks = totalDays / 7;
//How long is a month? 28, 29, 30 or 31 days?
var years = totalDays / 365;
if (years < 1) return weeks.ToString() + " weeks";
var decades = years / 10;
if (decades < 1) return years.ToString() + " years";
var centuries = decades / 10;
if (centuries < 1) return decades.ToString() + " decades";
var millenia = centuries / 10;
if (millenia < 1) return centuries.ToString() + " centuries";
return millenia.ToString() + " millenia";
}

Here is solution for years, months using DateTime and Gregorian calendar (meaning leap years, calendar months). Then it uses the TimeSpan solution as already submitted.
static string ToMostNonZeroTime(long ms) {
const int hundretsNanosecondsInMillisecond = 10000;
long ticks = (long)ms * hundretsNanosecondsInMillisecond;
var dt = new DateTime(ticks);
if((dt.Year - 1) > 0) { // starts with 1
double daysToYear = (dt.DayOfYear - 1) * 1.0 / (DateTime.IsLeapYear(dt.Year) ? 366 : 365);
daysToYear += dt.Year - 1;
return $"{daysToYear:0.0} years";
}
if((dt.Month - 1) > 0) {
double daysToMonth = (dt.Day - 1) * 1.0 / DateTime.DaysInMonth(dt.Year, dt.Month);
daysToMonth += dt.Day - 1;
return $"{daysToMonth:0.0} months";
}
// can use TimeSpan then:
var ts = TimeSpan.FromMilliseconds(ms);
if(ts.TotalDays >= 1)
return $"{ts.TotalDays:0.0} days";
if(ts.TotalHours >= 1)
return $"{ts.TotalHours:0.0} hours";
if(ts.TotalMinutes >= 1)
return $"{ts.TotalMinutes:0.0} minutes";
if(ts.TotalSeconds >= 1)
return $"{ts.TotalSeconds:0.0} seconds";
return $"{ms} milliseconds";
}
It prints
100ms: 100 milliseconds
1000ms: 1.0 seconds
10000ms: 10.0 seconds
100000ms: 1.7 minutes
1000000ms: 16.7 minutes
10000000ms: 2.8 hours
100000000ms: 1.2 days
1000000000ms: 11.6 days
20000000000ms: 19.6 months
200000000000ms: 6.3 years
Have a look at https://ideone.com/QZHOM4

How to calculate remaining minutes to "next" half an hour or hour?

I would like to calculate the remaining minutes to the "next" half an hour or hour.
Say i get a start time string of 07:15, i want it to calculate the remaining minutes to the nearest half an hour (07:30).
That would be 15min.
Then i can also have an instance where the start time can be 07:45 and i want it to calculate the remaining minutes to the nearest hour (08:00).
That would also be 15min.
So any string less then 30min in a hour would calculate to the nearest half an hour (..:30) and any string over 30min would calculate to the nearest hour (..:00).
I don't want to do a bunch of if statements, because i get from time strings that can start from and minute in an hour.
This is what i do not want to do:
if (int.Parse(fromTimeString.Right(2)) < 30)
{
//Do Calculation
}
else
{
//Do Calculation
}
public static string Right(this String stringValue, int noOfCharacters)
{
string result = null;
if (stringValue.Length >= noOfCharacters)
{
result = stringValue.Substring(stringValue.Length - noOfCharacters, noOfCharacters);
}
else
{
result = "";
}
return result;
}
Is there not an easier way with linq or with the DateTime class

Use modulo operator % with 30. Your result will be equal to (60 - currentMinutes) % 30. About LINQ its used for collections so i can't realy see how it can be used in your case.

You can use this DateTime tick-round approach to get the timespan until next half hour:
var minutes = 30;
var now = DateTime.Now;
var ticksMin = TimeSpan.FromMinutes(minutes).Ticks;
DateTime rounded = new DateTime(((now.Ticks + (ticksMin/2)) / ticksMin) * ticksMin);
var diff=rounded-now;
var minUntilNext = diff.TotalMinutes > 0 ? diff.TotalMinutes : minutes + diff.TotalMinutes;

var minutesToNextHalfHour = (60 - yourDateTimeVariable.Minutes) % 30;

This should do it:
int remainingMinutes = (current.Minute >= 30)
? 60 - current.Minute
: 30 - current.Minute;

var hhmm = fromTimeString.Split(':');
var mins = int.Parse(hhmm[1]);
var remainingMins = (60 - mins) % 30;

var str = "7:16";
var datetime = DateTime.ParseExact(str, "h:mm", new CultureInfo("en-US"));
var minutesPastHalfHour = datetime.Minute % 30;
var minutesBeforeHalfHour = 30 - minutesPastHalfHour;

I would use modulo + TimeSpan.TryParse:
public static int ComputeTime(string time)
{
TimeSpan ts;
if (TimeSpan.TryParse(time, out ts))
{
return (60 - ts.Minutes) % 30;
}
throw new ArgumentException("Time is not valid", "time");
}
private static void Main(string[] args)
{
string test1 = "7:27";
string test2 = "7:42";
Console.WriteLine(ComputeTime(test1));
Console.WriteLine(ComputeTime(test2));
Console.ReadLine();
}

Datetime according to Client location

I have The Date time in UTC in database, now I want to show that time according to the User's Timezone or user's computer machine, like if user A has summit a question from India then User A can see the Submitted date according to India, if user A goes to USA then it shows according to USA, and if User B is in China then He can view that question according to China.
how can I do that via C# or javascript.
any one can help me to do that.

You will need to use JavaScript to gather the necessary information from the browser - for this part see http://www.pageloom.com/automatic-timezone-detection-with-javascript
When you have this information you can setup a TimeZone / TimeZoneInfo which in turn can be used to adjust your UTC DateTime values.
Another easier option is using a jQuery plugin called TimeAgo.
For details see C# UTC to Users Local Time

you can do like this.. by using javascript.....
This code will give you client time zone offset in standard format....
<script type="text/javascript">
// Original script by Josh Fraser (http://www.onlineaspect.com)
// Some customization applied in this script code
var minutes;
function calculate_time_zone() {
var rightNow = new Date();
var jan1 = new Date(rightNow.getFullYear(), 0, 1, 0, 0, 0, 0); // jan 1st
var june1 = new Date(rightNow.getFullYear(), 6, 1, 0, 0, 0, 0); // june 1st
var temp = jan1.toGMTString();
var jan2 = new Date(temp.substring(0, temp.lastIndexOf(" ") - 1));
temp = june1.toGMTString();
var june2 = new Date(temp.substring(0, temp.lastIndexOf(" ") - 1));
var std_time_offset = (jan1 - jan2) / (1000 * 60 * 60);
var daylight_time_offset = (june1 - june2) / (1000 * 60 * 60);
var dst;
if (std_time_offset == daylight_time_offset) {
dst = "0"; // daylight savings time is NOT observed
} else {
// positive is southern, negative is northern hemisphere
var hemisphere = std_time_offset - daylight_time_offset;
if (hemisphere >= 0)
std_time_offset = daylight_time_offset;
dst = "1"; // daylight savings time is observed
}
var i;
// Here set the value of hidden field to the ClientTimeZone.
minutes = convert(std_time_offset);
TimeField = document.getElementById("HiddenFieldClientTime");
TimeField.value = minutes;
alert('your time zone is ' + minutes);
}
// This function is to convert the timezoneoffset to Standard format
function convert(value) {
var hours = parseInt(value);
value -= parseInt(value);
value *= 60;
var mins = parseInt(value);
value -= parseInt(value);
value *= 60;
var secs = parseInt(value);
var display_hours = hours;
// handle GMT case (00:00)
if (hours == 0) {
display_hours = "00";
} else if (hours > 0) {
// add a plus sign and perhaps an extra 0
display_hours = (hours < 10) ? "+0" + hours : "+" + hours;
} else {
// add an extra 0 if needed
display_hours = (hours > -10) ? "-0" + Math.abs(hours) : hours;
}
mins = (mins < 10) ? "0" + mins : mins;
return display_hours + ":" + mins;
}
// Adding the function to onload event of document object
onload = calculate_time_zone;
</script>
I recommended you pls go through this link
and take a look at this one also time detection