Modifying information of DateTime in C#

Question

4.00/5 (1 vote)

See more:

Hey it's me again. I'm happy because all of you help me to make my job easier.

I have a simple but big problem:

//a date with an hour
DateTime date = DateTime.Parse("2011-02-01 00:23:50");
//I tried doing this too:
DateTime date = new DateTime(2011,2,1,0,23,50);

//It doesn't work and I don't know why:
date.AddHour(-1);
// It doesn't work eighter
date.AddDay(1);

I want to substract an hour from this datetime I should have something like this: 2011-01-31 23:23:50
The fact is that I want to add or substract anything I want (a year, day, month, hour, minute or second) and not just an hour. Is there any automatic function?

Thanks!

Posted 2-Feb-11 11:57am

pancho2413

Updated 2-Feb-11 11:59am

v2

Add a Solution

2 solutions

Solution 1

OH MIGHTLY GOD!

I didn't realize it was such an easy solucion:

date.AddHour(-1) is a function that returns a DateTime with the new information, so if I don't assign the new value to any variable I will have the same problem forever:

here is the solution:

date = date.AddHour(-1);

Posted 2-Feb-11 12:14pm

pancho2413

Comments

Sergey Alexandrovich Kryukov 2-Feb-11 21:40pm

Unfortunately, this is not universal solution you were asking for.
You can find the solution in my answer.
--SA

Sandeep Mewara 2-Feb-11 23:59pm

Surely one of the way, but this would only go for defined hours. (or similar for minutes or seconds) BUT not for all of them at once.

If you really want to add/remove some hours-minutes-seconds from a given DateTime then Timespan is the way.

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Accepted Answer · 2011-02-02T12:22:00

Don't forget, time and duration are different things. You also need duration. Time is represented by DataTime, but duration — more powerful for time arithmetics — by TimeSpan. Is my hint already taken?

If not, please keep reading:

C#

DateTime time = DateTime.Now;
int days = 13;
int hours = 12;
int minutes = 55;
int seconds = 12;
time -= new TimeSpan(days, hours, minutes, seconds);

//lookup all the overloaded constructors for more detail...

time += new TimeSpan(days, hours);

Now the idea should be completely clear for you. With TimeSpan, you can do any reasonable time arithmetic operation you might expect.

Side note: one useful application of such arithmetic operations is measuring time: you can subtract one time from another, returned result is TimeSpan:

C#

DateTime before = DateTime.Now;
//some timely operation here
DateTime after = DateTime.Now;

TimeSpan delay = after - before;
double ms = delay.TotalMilliseconds;
double hours = delay.TotalHours;

//...

—SA