Develop Reference

Change the time forward

I am getting dates from the database and for each date I want to change the time forward starting from the DateTime that was obtained from the database until I get to a given Fixed Time (Y). However, (Y) might be in the next day.
For example if the date from the database is [7/6/2017 5:00:00 AM] and the given Fixed Time is 10:00 PM then I want to get [7/6/2017 10:00:00 PM].
However if the fixed time is 02:00 AM then I want to get [7/7/2017 02:00:00 AM] (notice that the date has increased by one)
Note: The code is running, but I modified the code to make it shorter and make more sense. Thus, there might be syntax or spelling mistakes.
My first solution was something like this:
private DateTime setTimeForeward(DateTime date) {
DateTime today = DateTime.ParseExact(FixedTime, "hh:mm tt", CultureInfo.InvariantCulture);
TimeSpan difference = today.TimeOfDay - date.TimeOfDay;
return date + difference;
}
That didn't work as expected when the fixed time is 02:00 AM. The difference becomes negative( it doesn't go around the clock) and the date will be [7/6/2017 02:00:00 AM].
I ended up with the following code
private DateTime setTimeForeward(DateTime date) {
DateTime today = DateTime.ParseExact(FixedTime "hh:mm tt", CultureInfo.InvariantCulture);
TimeSpan difference = today.TimeOfDay - date.TimeOfDay;
if (difference.Hours < 0) {
difference += new TimeSpan(24, 0, 0);
}
return date + difference;
}
I am not sure if my function is logically correct and I feel like I am overthinking it. Also,I am not sure if there's a better way or a built in function that does what I want for me. Basically, I am looking for a correct and an elegant solution.
Thank you very much in advanced.

In this method, I'm using DateTime fixedTime to represent a time. I don't really care about it's Day, Month, and Year values.
static DateTime GetClosingTime(DateTime fixedTime, DateTime dbTime)
{
var cutoff = new DateTime(dbTime.Year, dbTime.Month, dbTime.Day, fixedTime.Hour, fixedTime.Minute, fixedTime.Second);
if (dbTime < cutoff)
return cutoff;
else
{
cutoff = cutoff.AddDays(1);
return cutoff;
}
}
Here's calling it with your provided example input.
var FixedTime10PM = new DateTime(1, 1, 1, 22, 0, 0);
var FixedTime02AM = new DateTime(1, 1, 1, 2, 0, 0);
var dbTime = new DateTime(2018, 6, 20, 5, 0, 0);
var dt1 = GetClosingTime(FixedTime10PM, dbTime);
var dt2 = GetClosingTime(FixedTime02AM, dbTime);
Console.WriteLine(dt1.ToLongDateString() + " " + dt1.ToLongTimeString());
Console.WriteLine(dt2.ToLongDateString() + " " + dt2.ToLongTimeString());
And here's my output:
EDIT:
Simplified method based on suggestions in comments:
static DateTime GetClosingTime(DateTime fixedTime, DateTime dbTime)
{
var cutoff = new DateTime(dbTime.Year, dbTime.Month, dbTime.Day, fixedTime.Hour, fixedTime.Minute, fixedTime.Second);
return dbTime < cutoff ? cutoff : cutoff.AddDays(1);
}

Your logic is almost right but you shouldn't be checking for difference.Hours because there might be a difference in minutes (or even seconds if you changed the format later).
I adjusted your function and changed some variable names to make them easier to follow:
private DateTime SetTimeForward(DateTime originalDate)
{
TimeSpan newTime = DateTime.ParseExact(FixedTime,
"hh:mm tt",
CultureInfo.InvariantCulture).TimeOfDay;
TimeSpan diff = newTime - originalDate.TimeOfDay;
if (diff.Ticks < 0)
diff = diff.Add(new TimeSpan(24, 0, 0));
return originalDate.Add(diff);
}
Some remarks:
If your FixedTime is really fixed, you might want to store it directly as a TimeSpan so you don't have to parse it every time.
If you parse the FixedTime because it's changeable, you might pass it as a second argument instead:
private DateTime SetTimeForward(DateTime originalDate, string fixedTime)
Or:
private DateTime SetTimeForward(DateTime originalDate, TimeSpan newTime)
The current implementation does not change the date value if the newTime is equal to originalDate.TimeOfDay. I.E., If the originalDate is 7/6/2017 2:00 AM and the FixedTime/newTime is 02:00 AM, the returned date will be equal to the originalDate. If that's not your desired behavior, you might change diff.Ticks < 0 to diff.Ticks <= 0.

Slightly different approach:
private DateTime setTimeForeward(DateTime date)
{
var targetTimeOfDay = TimeSpan.ParseExact(FixedTime, "hh:mm tt", CultureInfo.InvariantCulture);
if (targetTimeOfDay < date.TimeOfDay)
{
date = date.AddDays(1);
}
return date.Date + targetTimeOfDay;
}
I'm getting target time as TimeSpan from the beginning instead of creating DateTime and getting TimeOfDay (which is TimeSpan).
Then I check if the target time of day is lower than time to be modified and if it is I add one day.
I use date.Date + targetTimeOfDay as return value as date.Date will return date with time set to 00:00 and adding target time to it will already set the target hour without calculating the difference.

Difference between two times C# [duplicate]

How do I get the time difference between two DateTime objects using C#?

The following example demonstrates how to do this:
DateTime a = new DateTime(2010, 05, 12, 13, 15, 00);
DateTime b = new DateTime(2010, 05, 12, 13, 45, 00);
Console.WriteLine(b.Subtract(a).TotalMinutes);
When executed this prints "30" since there is a 30 minute difference between the date/times.
The result of DateTime.Subtract(DateTime x) is a TimeSpan Object which gives other useful properties.

You want the TimeSpan struct:
TimeSpan diff = dateTime1 - dateTime2;
A TimeSpan object represents a time interval (duration of time or elapsed time) that is measured as a positive or negative number of days, hours, minutes, seconds, and fractions of a second. The TimeSpan structure can also be used to represent the time of day, but only if the time is unrelated to a particular date.
There are various methods for getting the days, hours, minutes, seconds and milliseconds back from this structure.
If you are just interested in the difference then:
TimeSpan diff = (dateTime1 - dateTime2)).Duration();
will give you the positive difference between the times regardless of the order.
If you have just got the time component but the times could be split by midnight then you need to add 24 hours to the span to get the actual difference:
TimeSpan diff = dateTime1 - dateTime2;
if (diff < 0)
{
diff = diff + TimeSpan.FromDays(1);
}

What you need is to use the DateTime classs Subtract method, which returns a TimeSpan.
var dateOne = DateTime.Now;
var dateTwo = DateTime.Now.AddMinutes(-5);
var diff = dateTwo.Subtract(dateOne);
var res = String.Format("{0}:{1}:{2}", diff.Hours,diff.Minutes,diff.Seconds));

The way I usually do it is subtracting the two DateTime and this gets me a TimeSpan that will tell me the diff.
Here's an example:
DateTime start = DateTime.Now;
// Do some work
TimeSpan timeDiff = DateTime.Now - start;
timeDiff.TotalMilliseconds;

IF they are both UTC date-time values you can do TimeSpan diff = dateTime1 - dateTime2;
Otherwise your chance of getting the correct answer in every single possible case is zero.

var startDate = new DateTime(2007, 3, 24);
var endDate = new DateTime(2009, 6, 26);
var dateDiff = endDate.Subtract(startDate);
var date = string.Format("{0} years {1} months {2} days", (int)dateDiff.TotalDays / 365,
(int)(dateDiff.TotalDays % 365) / 30, (int)(dateDiff.TotalDays % 365) / 30);
Console.WriteLine(date);

private void button1_Click(object sender, EventArgs e)
{
TimeSpan timespan;
timespan = dateTimePicker2.Value - dateTimePicker1.Value;
int timeDifference = timespan.Days;
MessageBox.Show(timeDifference.ToString());
}

You can use in following manner to achieve difference between two Datetime Object. Suppose there are DateTime objects dt1 and dt2 then the code.
TimeSpan diff = dt2.Subtract(dt1);

You need to use a TimeSpan. Here is some sample code:
TimeSpan sincelast = TimeSpan.FromTicks(DateTime.Now.Ticks - LastUpdate.Ticks);

Difference between times entered as text

i am new to c# and i have been trying to create a code that shows the total number of hours worked..eg a person working from 8am to 4pm means he works 8 hrs a day.
i want a code that shows how many hours he worked.
i tried for loop but i am not getting it right..
please help me out
int from = Convert.ToInt32(frA.Text);
int to = Convert.ToInt32(toA.Text);
for (from = 0; from <= to; from++)
{
totalA.Text = from.ToString();
}

A loop isn't what you need here. You could use DateTime and a Timespan:
DateTime start = new DateTime(2013, 07, 04, 08,00, 00);
DateTime end = new DateTime(2013, 07, 04, 16,00, 00);
TimeSpan ts = end - start;
Console.Write(ts.Hours);
Here I create two DateTime objects for today (04/07/2013). One has the start time of 08:00 and the end time 16:00 (4pm).
The Timespan object ts subtracts these dates, you can then use the .Hours property.

You first have to convert the string to int, then you can initialize a TimeSpan struct:
int from, to;
if (int.TryParse(frA.Text, out from) && int.TryParse(toA.Text, out to))
{
if (to <= from)
MessageBox.Show("To must be greater than From.");
else
{
TimeSpan workingHours = TimeSpan.FromHours(to - from);
// now you have the timespan
int hours = workingHours.Hours;
double minutes = workingHours.TotalMinutes;
// ...
}
}
else
MessageBox.Show("Please enter valid hours.");
You don't really need the TimeSpan here, you could also use the int alone. Used it anyway to show that it allows to provide other properties like minutes or second.

If that inputs can be taken to DateTime, then you can do it like the following line of code
double totalHours = (DateTime.Now - DateTime.Now).TotalHours;

How to set current time to a value

I was just wondering if there is a way to get the current time and set it into a value.
If its 12:06 AM.. I want to get that time and set it into currentTime.
Example
float currentTime = 0;
currentTime = 12.06;

As others have mentioned, the DateTime class would be ideal for this, and to work out the difference between 2 date/times:
DateTime end = DateTime.Now;
DateTime start = new DateTime(2011, 12, 5, 12, 6,0);
double hours = (end - start).TotalHours;
The subtraction of DateTime objects results in a TimeSpan object that you can use to see the hours/minutes etc.

try DateTime class
DateTime dt = DateTime.Now;

Is this what you're looking for?
DateTime currentTime;
currentTime = DateTime.Now;

Don't use floats or strings. You can do all kinds of cool things using DateTime.
Here's how you'd get the hours that someone worked:
var clockIn = new DateTime(2011,12,4,9,0,0); // December 4th, 9 AM
var clockOut = new DateTime(2011,12,4,17,0,0); // December 4th, 5 PM
var duration = clockOut - clockIn; // TimeSpan
Console.Write(duration.TotalHours); // 8

A few people have mentioned how, but as a 'better' recommendation you should use
DateTime currentTime = DateTime.UtcNow
Otherwise you have issues when the clocks go back, if your timing code is run on those days. (plus it is far easier to alter the UTC time to local time than it is to convert a '1am' to UTC (as there will be two of them when the clocks go back)

Well if you really what it as a float then try:
var currentDate = DateTime.Now;
float currentTime = float.Parse((currentDate.Hour > 12 ? currentDate.Hour -12 :
currentDate.Hour) + "." + currentDate.Minute);
I wouldn't recommend comparing dates or time with floats. A better options would be to use timespans.

You should be using a Timespan instance for time related values, you can use the flexibility to get the required values like
TimeSpan ts = DateTime.Now.TimeOfDay;
ts.ToString("hh:mm") // this could be what you are looking for
You could then use ts.TotalHours which would give you fractional hours (as a double) else you could construct a string specifically using ts.Hours ..ts.Minutes play around and it could be prove useful.

Try the following:
DateTime StartTime=StartTime value;
DateTime CurrentTime=DateTime.Now;
TimeSpan dt = CurrentTime.Subtract(StartTime);
In dt you will get a working time period.

If you want to have the difference between two times, then do this:
DateTime dateOne = DateTime.Parse(enteredTime);
DateTime dateTwo = DateTime.Now;
TimeSpan difference = dateOne - dateTwo;

Date comparison - How to check if 20 minutes have passed?

How to check if 20 minutes have passed from current date?
For example:
var start = DateTime.Now;
var oldDate = "08/10/2011 23:50:31";
if(start ??) {
//20 minutes were passed from start
}
what's the best way to do this?
Thanks :)

You should convert your start time to a UTC time, say 'start'.
You can now compare your start time to the current UTC time using:
DateTime.UtcNow > start.AddMinutes(20)
This approach means that you will get the correct answer around daylight savings time changes.
By adding time to the start time instead of subtracting and comparing the total time on a TimeSpan you have a more readable syntax AND you can handle more date difference cases, e.g. 1 month from the start, 2 weeks from the start, ...

var start = DateTime.Now;
var oldDate = DateTime.Parse("08/10/2011 23:50:31");
if ((start - oldDate).TotalMinutes >= 20)
{
//20 minutes were passed from start
}

var start = DateTime.Now;
var oldDate = DateTime.Parse("08/10/2011 23:50:31");
if(start.Subtract(oldDate) >= TimeSpan.FromMinutes(20))
{
//20 minutes were passed from start
}

Parse oldDate into a DateTime object (DateTime.Parse).
Subtract the parsed date from start. This will return a TimeSpan.
Inspect TotalMinutes.

I was able to accomplish this by using a JodaTime Library in my project. I came out with this code.
String datetime1 = "2012/08/24 05:22:34";
String datetime2 = "2012/08/24 05:23:28";
DateTimeFormatter format = DateTimeFormat.forPattern("yyyy/MM/dd HH:mm:ss");
DateTime time1 = format.parseDateTime(datetime1);
DateTime time2 = format.parseDateTime(datetime2);
Minutes Interval = Minutes.minutesBetween(time1, time2);
Minutes minInterval = Minutes.minutes(20);
if(Interval.isGreaterThan(minInterval)){
return true;
}
else{
return false;
}
This will check if the Time Interval between datetime1 and datetime2 is GreaterThan 20 Minutes. Change the property to Seconds. It will be easier for you know. This will return false.

var end = DateTime.Parse(oldDate);
if (start.Hour == end.Hour && start.AddMinutes(20).Minute >= end.Minute)