Re: How to compare two Times - C# Discussion Boards

Mali Perica14-Jun-07 1:30

Mali Perica

14-Jun-07 1:30

For hours and minutes only, without dates and seconds:

DateTime first;
DateTime second;

if (first.Hour > second.Hour)
{
    //first is later
}
else
    if (first.Hour == second.Hour)
        if (first.Minute > second.Minute)
        {
            //first is later
        }
        else
            if (first.Minute == second.Minute)
            {
                //they are the same
            }
            else
            {
                //second is later
            }
    else
    {
        //second is later
    }

Martin#14-Jun-07 1:31

Martin#

14-Jun-07 1:31

Hello,

Look at System.TimeSpan class.

All the best,

Martin

Muammar©14-Jun-07 1:37

Muammar©

14-Jun-07 1:37

TimeSpan is what you need.

Smile: A curve that can set a lot of things straight!
(\ /)
(O.o)
(><)

Dewald14-Jun-07 1:45

14-Jun-07 1:45

Yu can use the System.TimeSpan class. Quite handy, especially when used in conjunction with System.DateTime.

<br />
DateTime dt1 = DateTime.Parse("2007/06/14 13:24:00");<br />
DateTime dt2 = DateTime.Parse("2007/06/14 12:00:00");<br />
TimeSpan ts = dt1 - dt2;<br />
double elapsed = ts.TotalHours;<br />

This will give you the total number of hours elapsed from dt1 until dt2. If you are rather interested in the total number of minutes that elapsed you can use:
double elapse = ts.TotalMiutes;
or a host of others.

Luc Pattyn14-Jun-07 3:07

Luc Pattyn

14-Jun-07 3:07

Hi,

if you want to ignore the other fields in a DateTime, you can not easily use the available
functions, nor TimeSpan.

I then suggest something like this:

public static int CompareHourMinuteOnly(DateTime dt1, DateTime dt2) {
    int diff=dt1.Hour-dt2.Hour;
    if (diff==0) diff=dt1.Minute-dt2.Minute;
    return diff;
}

Luc Pattyn

[My Articles] [Forum Guidelines]

andreumv14-Jun-07 3:50

andreumv

14-Jun-07 3:50

Ramana. G.V wrote:
how to compare two times using DateTime object. I need to compare hours & minutes only based on this i am showing some message.

If DateTimeObject1.TimeOfDay = DatTimeObject2.TimeOfDay Then<br />
 'do something<br />
End If

Martin#14-Jun-07 4:01

Martin#

14-Jun-07 4:01

Hmm,

It's not an answere to the question, and it's not C# code!

upload file C# web application

Le centriste14-Jun-07 7:21

Le centriste

14-Jun-07 7:21

Another way would be to force the 2 DateTime instances to have the same date (hardcode to something like 0001-01-01) and then do a DateTime.Compare(d1, d2);

-----

Formerly MP(2)

If atheism is a religion, then not collecting stamps is a hobby. -- Unknown

reddyamar_uk14-Jun-07 0:56

reddyamar_uk

14-Jun-07 0:56

Hi,

Can any one please give me a script to browse and upload a file to a specific webserver location which should also check the extension of the file ( for eg, css files needs to go into one location and graphics files need to go into another location)

Thank You.

Re: upload file C# web application

giddy_guitarist17-Jun-07 10:16

giddy_guitarist

17-Jun-07 10:16

have a look at the WebClient class:
System.Net.WebClient[^]

Question on iterators

Dewald14-Jun-07 0:13

14-Jun-07 0:13

So I have a class for which I wrote a nice indexer, making it possible to access the class contents as if it were an array. Some like this:

public class MyClass
{
   protected byte[] buffer;
   protected int size;

   public byte this[int index]
   {
      get
      {
         if (index<0 || index >= size)
            throw new IndexOutOfRangeException();
         return buffer[index];
      }
      set
      {
         if (index<0 || index >= size)
            throw new IndexOutOfRangeException();
         buffer[index] = value;
      }
   }
}

Now I'd like to pass this entire class (the array'ed version so to speak) as a parameter to a function. Say I have a function defined as follows:
public void myFunc (byte[] inbuffer)

Obviously I can't call this function as follows:

MyClass myInstance = new MyClass();<br />
myFunc (myInstance);

because it will give a compile time error of cannot convert from 'MyClass' to 'byte[]'

So even though, through the very nice functionalty of indexers, I can access the class as an array, I still can't pass it as an array. Is there a way that I'm just not aware of?

Colin Angus Mackay14-Jun-07 0:35

Colin Angus Mackay

14-Jun-07 0:35

Dewald wrote:
Is there a way that I'm just not aware of?

Not really. What is happening is all just syntactic sugar. It looks like an array but you know that it isn't really an array. Therefore, if you want it to be an array you have to convert it to one.

My suggestion would be to add a method called GetAsByteArray() or similar and the contents of the method would create and return this byte array.

Returning the internal buffer should be avoided as it would be possible for something outside your class to modify the contents and your class wouldn't know about it. That would break the encapsulation aspect of OO.

Upcoming events:
* Glasgow: Mock Objects, SQL Server CLR Integration, Reporting Services, db4o, Dependency Injection with Spring ...
* Reading: Developer Day 5

Never write for other people. Write for yourself, because you have a passion for it. -- Marc Clifton

My website

Dewald14-Jun-07 1:28

14-Jun-07 1:28

Thanks Colin,

I was starting to think that I should probably use something like a GetAsByteArray() method but then it occured to me that it should be possible to override the implicit cast operator and would you believe!

I now have the following piece of code in my class:

static public implicit operator byte[](MyClass m)
{
   return (byte[])m.buffer.Clone();
}

... and Bob's your uncle.

The reason I'm using the Clone() method of Array is so that I don't pass the array reference itself which, as you pointed out, would break the aspect of encapsulation.

Colin Angus Mackay14-Jun-07 2:04

Colin Angus Mackay

14-Jun-07 2:04

Dewald wrote:
it occured to me that it should be possible to override the implicit cast operator

I suppose. I'm not a fan of that sort of thing as many classes could be converted in many ways and I prefer to make it explicit what sort of conversion is going on.

The casting operator makes it look like is something as simple as a casting the class to its base, which is a fast operation. Where as a conversion is potentially quite slow.

Anyway, that's just my opinion and it is your project.

Dewald14-Jun-07 2:21

14-Jun-07 2:21

Fair point. I'm still undecided as to whether I really like this approach. For what I was trying to do, this works perfectly but I'm not sure if it is really a good programming practice.

I am busy porting code from a C++ project to C#. In the C++ project I have a structure with a number of member variables which I'm sending across a TCP socket to a server. The server then responds and the response is copied into another structure.

So what I used to do was to take a pointer of the structure and cast it to a byte array and when the response comes back to take the byte array again and cast it to a pointer to the structure. This was a very quick way of obtaining a stream of bytes from the structure or populating the structure with a stream of bytes but in itself probably not a safe programming practice to start off with. The issues of endianness, memory overflow etc. etc. had to be handled manually and C# is big step towards taking that responsibility off the programmer and managing all of it automatically.

So this "sollution" of mine is probably a step in the opposite direction of what C# have been designed to achieve.

Thanks for the help though.

Luc Pattyn14-Jun-07 1:27

Luc Pattyn

14-Jun-07 1:27

Hi,

I dont think it is possible; you would need something like an Indexable interface,
which then also would have been implemented by an array.

BTW I think your index testing code can be omitted, it seems to serve no purpose.

Smile | :)

Luc Pattyn

[My Articles] [Forum Guidelines]

Dewald14-Jun-07 2:02

14-Jun-07 2:02

Luc Pattyn wrote:
BTW I think your index testing code can be omitted, it seems to serve no purpose.

LOL. Of course. That was a nice bit of silly coding. Thanks for pointing it out.

As for it being impossible to pass the class as an array to a function, have a look at my response to Colin's answer. It seems to be possible after all. I'm a little undecided as to whether this is really good programming practice but it works and it solves my current problem perfectly.

Luc Pattyn14-Jun-07 2:19

Luc Pattyn

14-Jun-07 2:19

Hi,

I did consider the implicit cast approach, but I rejected the idea because
one either must pass the original array making it publicly writable (without cloning)
or copy everything (with cloning) which I consider unacceptable just to solve an
accessibility problem, for many reasons:
- the overhead involved
- the fact that a new (possibly big) object gets created without the programmer
being aware of it.

So IMO another approach is needed, such as modifying the method that consumes the array,
into consuming an interface (IIndexable), and implementing that interface in the indexable
class, plus adding a class that implements the same interface for regular arrays.

Smile | :)

Luc Pattyn

[My Articles] [Forum Guidelines]