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How to check, is “X minutes” passed with timeStamp in C#?

I am trying to create script that checks is the current time passed, but getting some errors.
DateTime currentTime = DateTime.Now;
TimeSpan pauseMin = TimeSpan.FromMinutes(1);
TimeSpan compare = currentTime + pauseMin;
if (currentTime >= compare)
return null;

I would write this as
DateTime currentTime = DateTime.Now;
TimeSpan pauseMin = TimeSpan.FromMinutes(1);
DateTime compare = currentTime.Add(pauseMin);
if (currentTime >= compare) {
return null;
}
This uses the type of object that you are trying to represent with everything. DateTime's can have Timespan's added to them: https://msdn.microsoft.com/en-us/library/system.datetime.add%28v=vs.110%29.aspx?f=255&MSPPError=-2147217396
Or Istern's answer if you are always just adding an integer of minutes to the time.

You can't compare DateTime and TimeSpan.
Try
var compare = currentTime.AddMinutes(1)
If you need to somehow use TimeSpan, use Jamie F's answer.

DateTime and TimeSpan is different. You can use currentTime like this:
TimeSpan currentTime = TimeSpan.FromTicks(DateTime.Now.Ticks);
And you can get passed minutes like this:
double minutes = (compare - currentTime).TotalMinutes;

If you just want to pause for 1 minute, you can use
System.Threading.Thread.Sleep(1000 * 60); // 1 minute = 60000 milliseconds
If you want your function to run for 1 minute, you can use something like
var returnAt = DateTime.Now().AddMinutes(1);
while ( true )
{
// your code here ?
if ( DateTime.Now() >= returnAt ) return null;
}

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;

how to get no of days and nights between two dates using c#

i am doing a project on cab services.in this rate is different for day and night.
in the form only journey start date and end date is selected.based on this i have to calculate the no of days and nights.
here i am confused how to calculate the no of days and night.
thanks in advance.

private List<DateTime> GetDateRange(DateTime StartingDate, DateTime EndingDate)
{
if (StartingDate > EndingDate)
{
return null;
}
List<DateTime> rv = new List<DateTime>();
DateTime tmpDate = StartingDate;
do
{
rv.Add(tmpDate);
tmpDate = tmpDate.AddDays(1);
} while (tmpDate <= EndingDate);
return rv;
}
To view this code in action, copy and paste the following code into SnippetCompiler:
DateTime StartingDate = DateTime.Parse("02/25/2007");
DateTime EndingDate = DateTime.Parse("03/06/2007");
foreach (DateTime date in GetDateRange(StartingDate,EndingDate))
{
WL(date.ToShortDateString());
}
Sample output :
2/25/2007
2/26/2007
2/27/2007
2/28/2007
3/1/2007
3/2/2007
3/3/2007
3/4/2007
3/5/2007
3/6/2007

Use the Subtract method to get the difference, which is a TimeSpan value. Example:
TimeSpan diff = SecondDate.Subtract(FirstDate);
You can get the length of the time span for example in hours:
double hours = diff.TotalHours;
I'm not sure which time unit "days and nights" could be interpreted as, though. Perhaps days?
double days = diff.TotalDays;

DateTime dt1,dt2;
//...
TimeSpan period = dt1 - dt2;
int days = period.Days;

It sounds like a very long Cab journey that takes days and nights!
I think you need to define what a day and a night is more clearly in order to get your perfect answer. You also need to think about what impact Daylight Saving Time has on your calculations.
If say:
a day was the period from 6am to 6pm
the night was the rest - from 6pm to 6am
and you wanted to really count hours rather than days
In this case then a calculation would require you to:
iterate a currentDateTime from the startDateTime to the endDateTime
choose the increment in the currentDateTime so that it jumps to the next time barrier (6am, 6pm or the endDateTime)
within each loop, then add to your cumulative calculation of numDayHours or numNightHours so far.
Note that:
you could make this calculation quicker by counting whole days along the way
you need to be very careful about the time zone you are calculating in (I just hope that your taxi doesn't cross time zone boundaries!)
you need to be very careful about local time changes - especially "daylight savings time" type changes - the duration from 6pm to 6am is not always 12 hours!
Some pseudo code:
var numDayHours = 0.0;
var numNightHours = 0.0;
var current = startDateTime;
while (current < endDateTime)
{
next_hop = calculate_next_hop (current, endDateTime);
// select next date time
switch (next_hop.hop_type)
{
case HopType.night_time_hop:
numNightHours += next_hop.num_hours;
break;
case HopType.day_time_hop:
numDayHours += next_hop.num_hours;
break;
}
current = next_hop.EndDateTime;
}
// and here is the result
double numDays = numDayHours / 12.0;
double numHours = numNightHours / 12.0;

How to Handle Actual Time with Durations in C#?

What's the preferred approach to compare a complete DateTime instance with an hour, minute, and second which represents an actual time of day, with the ability to operate over those triplets (eg add hours, minutes seconds..)?
My current approach is something like
DateTime startHour = new DateTime(1900,1,1,12,25,43);
DateTime endHour = new DateTime(1900,1,1,13,45,32);
// I need to, say, know if a complete DateTime instance
// is later than startHour plus 15 minutes
DateTime now = DateTime.Now();
startHour = startHour.addMinutes(15);
if (now.CompareTo(new DateTime(now.Year, now.Month, now.Day, startHour.Hour,
startHour.Minute, startHour.Second)) > 0)
{
//I can do something now
}
This is very cumbersome and even failure prone. TimeSpans are not a solution as far as I can see, because they represent spans and aren't bound by the 24 hours limit (a TimeSpan of 56 hours 34 minutes is valid.)
What's the preferred approach for this type of calculations?

It's not at all clear what you mean by "is greater than startHour"... but taking
TimeSpan startHour = new TimeSpan(12, 25, 43);
if (endHour.TimeOfDay > startHour)
{
...
}
... works pretty simply.
By all means add argument checking to make sure that you don't specify a value for startHour which is < 0 or > 23 hours, but that's all pretty easy.
.NET's date and time API is quite primitive (even in 3.5) compared with, say, Joda Time - but in this particular case I think it's not too bad.

A little hint - .NET supports arithmetic operations on DateTime objects, and returns a TimeSpan object. Thus, you can do the following:
DateTime fromDate = ....
DateTime toDate = ....
TimeSpan diff = toDate - fromDate;
and you can expand this to:
DateTime fromDate = DateTime.Now;
DateTime toDate = DateTime.Now.addMinutes(x);
if ((toDate - fromDate).TotalMinutes > 15) {
...
}

You should use TimeSpan for startHour and endHour.
When comparing with now, you should "convert" them to a full DateTime or get the Time with DateTime.TimeOfDay as mentioned by Jon Skeet.
TimeSpan startHour = new TimeSpan(12, 25, 43);
DateTime now = DateTime.Now;
if (now.CompareTo(DateTime.Today.Add(startHour)) > 0) {
//...
}
or
TimeSpan startHour = new TimeSpan(12, 25, 43);
DateTime now = DateTime.Now;
if (now.TimeOfDay.CompareTo(startHour) > 0) {
//...
}

So you're only interested in the time component of the date.
if(DateTime.Now.TimeOfDay > startHour.TimeOfDay)
{
// do stuff
}
What's wrong with doing this?

DateTime of next 3am occurrence

I'm sure this is very easy, but I've got a sudden mental block.
I'm trying to get a DateTime object for the next occurence of 3am. For example, if DateTime.Now is 16/july/2009 : 12:04pm - the next occurance of 3am would be 17/july/2009 : 03:00
However, if DateTime.Now was 17/july/2009 : 01:00 then the next occurence would still be 17/july/2009 : 03:00 (not the day after).
Does that make sense?

One option:
DateTime now = DateTime.Now;
DateTime today3am = now.Date.AddHours(3);
DateTime next3am = now <= today3am ? today3am : today3am.AddDays(1);
Another:
DateTime now = DateTime.Now;
DateTime today = now.Date;
DateTime next3am = today.AddHours(3).AddDays(now.Hour >= 3 ? 1 : 0)
Lots of ways of skinning that particular cat :)
This is all in local time of course, which means you don't need to worry about time zones. Life becomes trickier if you want to get time zones involved...
Note that it's a good idea to take DateTime.Now once to avoid problems if the date rolls over while you're calculating...

DateTime now = DateTime.Now;
DateTime threeAM = now.Date.AddHours(3);
if (threeAM < now)
threeAM = threeAM.AddDays(1);

//just add 24 - 3 = 21 hours and get Today (start of day) and Add 3 hour
DateTime now = DateTime.Now.AddHours(21).Today.AddHours(3);

An alternative (using a function):
DateTime NextAt(TimeSpan time)
{
DateTime now = DateTime.Now;
DateTime result = now.Date + time;
return (now <= result) ? result : result.AddDays(1);
}
call it like:
DateTime next3am = NextAt(new TimeSpan(3,0,0));

You can do it without an if statement (or conditional operator):
// get the current time
DateTime now = DateTime.Now;
// get a 3:00 AM point in time in the future
DateTime next = now.Date.AddHours(24 + 3);
// subtract the number of whole extra days
next = next.AddDays((now - next).Days);
I always explain that you should get the point in time (DateTime.Now) only once in a calculation like this, as it's a changing value, so do I have to repeat it? Well, I just did. ;)

I think this One:
DateTime.Now.Date.AddHours(3).AddMinutes(0).AddSeconds(0).AddDays(1);