C#: what is the easiest way to subtract time?

问题

I\'m trying to put together a tool that will help me make work schedules. What is the easiest way to solve the following?

8:00am + 5 hours = 1:00pm

and

5:00pm - 2 hours = 3:00pm

and

5:30pm - :45 = 4:45

and so on.

回答1:

These can all be done with DateTime.Add(TimeSpan) since it supports positive and negative timespans.

DateTime original = new DateTime(year, month, day, 8, 0, 0);
DateTime updated = original.Add(new TimeSpan(5,0,0));

DateTime original = new DateTime(year, month, day, 17, 0, 0);
DateTime updated = original.Add(new TimeSpan(-2,0,0));

DateTime original = new DateTime(year, month, day, 17, 30, 0);
DateTime updated = original.Add(new TimeSpan(0,45,0));

Or you can also use the DateTime.Subtract(TimeSpan) method analogously.

回答2:

Check out all the DateTime methods here: http://msdn.microsoft.com/en-us/library/system.datetime.aspx

Add Returns a new DateTime that adds the value of the specified TimeSpan to the value of this instance.

AddDays Returns a new DateTime that adds the specified number of days to the value of this instance.

AddHours Returns a new DateTime that adds the specified number of hours to the value of this instance.

AddMilliseconds Returns a new DateTime that adds the specified number of milliseconds to the value of this instance.

AddMinutes Returns a new DateTime that adds the specified number of minutes to the value of this instance.

AddMonths Returns a new DateTime that adds the specified number of months to the value of this instance.

AddSeconds Returns a new DateTime that adds the specified number of seconds to the value of this instance.

AddTicks Returns a new DateTime that adds the specified number of ticks to the value of this instance.

AddYears Returns a new DateTime that adds the specified number of years to the value of this instance.

回答3:

This works too:

System.DateTime dTime = DateTime.Now();

// tSpan is 0 days, 1 hours, 30 minutes and 0 second.
System.TimeSpan tSpan = new System.TimeSpan(0, 1, 3, 0); 

System.DateTime result = dTime + tSpan;

To subtract a year:

DateTime DateEnd = DateTime.Now;
DateTime DateStart = DateEnd - new TimeSpan(365, 0, 0, 0);

回答4:

Use the TimeSpan object to capture your initial time element and use the methods such as AddHours or AddMinutes. To substract 3 hours, you will do AddHours(-3). To substract 45 mins, you will do AddMinutes(-45)

回答5:

Hi if you are going to subtract only Integer value from DateTime then you have to write code like this

DateTime.Now.AddHours(-2)

Here I am subtracting 2 hours from the current date and time

回答6:

try this

namespace dateandtime
{

    class DatesTime
    {

        public static DateTime Substract(DateTime now, int hours,int minutes,int seconds)
        {
            TimeSpan T1 = new TimeSpan(hours, minutes, seconds);
            return now.Subtract(T1);
        }


        static void Main(string[] args)
        {
            Console.WriteLine(Substract(DateTime.Now, 36, 0, 0).ToString());

        }
    }
}

来源：https://stackoverflow.com/questions/3993226/c-what-is-the-easiest-way-to-subtract-time

标签

datetime

math

timespan