DateTime range

[shapper]

Hello,

I have two nullable DateTime: begin and end.
I need to find the range, in month, between both variables.

If for some reason, for example begin is null, it is not possible to
calculate the range then I want to define the range as 1 month.

How can I do this?

Thanks,
Miguel

[=?ISO-8859-1?Q?Arne_Vajh=F8j?=]

Re: DateTime range

shapper wrote:

I have two nullable DateTime: begin and end.
I need to find the range, in month, between both variables.
>
If for some reason, for example begin is null, it is not possible to
calculate the range then I want to define the range as 1 month.
>
How can I do this?

I don't think there are any magic.

if(dt1 != null && dt2 != null)
{
delta = (dt2 - dt1).TotalMonth s;
}
else
{
delta = 1;
}

or something similar.

Arne

[shapper]

Re: DateTime range

On Oct 18, 6:40 pm, Arne Vajhøj <a...@vajhoej.d kwrote:

shapper wrote:

I have two nullable DateTime: begin and end.
I need to find the range, in month, between both variables.

>

If for some reason, for example begin is null, it is not possible to
calculate the range then I want to define the range as 1 month.

>

How can I do this?

>
I don't think there are any magic.
>
if(dt1 != null && dt2 != null)
{
     delta = (dt2 - dt1).TotalMonth s;}
>
else
{
     delta = 1;
>
}
>
or something similar.
>
Arne

In VB there is a really useful function named DateDiff. In C# there is
not ...

VisualBasic assembly could always be used but I prefer not to used
it ...

So I came up with the following:

int diff = 12 * (begin.Year - end.Year) + begin.Month - end.Month;
int months = Math.Abs(diff);

Not sure if it is the best option but I think I might implement a
DateDiff method for C#

[Peter Duniho]

Re: DateTime range

On Sat, 18 Oct 2008 11:39:43 -0700, shapper <mdmoura@gmail. comwrote:

In VB there is a really useful function named DateDiff. In C# there is
not ...

In C# there is no need. For that matter, DateDiff isn't really needed in
VB.NET. It's there for legacy reasons.

VisualBasic assembly could always be used but I prefer not to used
it ...

DateDiff doesn't address your original question. Why would you bother to
try to use it?

So I came up with the following:
>
int diff = 12 * (begin.Year - end.Year) + begin.Month - end.Month;
int months = Math.Abs(diff);

In what way does that address your original question?

Not sure if it is the best option but I think I might implement a
DateDiff method for C#

Why? What does DateDiff do for you that the operator- overload for
DateTime doesn't already?

Pete

[shapper]

Re: DateTime range

On Oct 18, 8:03 pm, "Peter Duniho" <NpOeStPe...@nn owslpianmk.com>
wrote:

On Sat, 18 Oct 2008 11:39:43 -0700, shapper <mdmo...@gmail. comwrote:

In VB there is a really useful function named DateDiff. In C# there is
not ...

>
In C# there is no need.  For that matter, DateDiff isn't really needed in  
VB.NET.  It's there for legacy reasons.
>

VisualBasic assembly could always be used but I prefer not to used
it ...

>
DateDiff doesn't address your original question.  Why would you bother to  
try to use it?
>

So I came up with the following:

>

int diff = 12 * (begin.Year - end.Year) + begin.Month - end.Month;
int months = Math.Abs(diff);

>
In what way does that address your original question?
>

Not sure if it is the best option but I think I might implement a
DateDiff method for C#

>
Why?  What does DateDiff do for you that the operator- overload for  
DateTime doesn't already?
>
Pete

Sorry Pete,

But does not my code calculate the difference between two dates in
months?

int diff = 12 * (begin.Year - end.Year) + begin.Month - end.Month;
int months = Math.Abs(diff);

I didn't address the nullable DateTime yet.

DateDiff, in my opinion, just creates an "easier" way to calculate
datetime spans in various intervals ...

[shapper]

Re: DateTime range

On Oct 18, 6:40 pm, Arne Vajhøj <a...@vajhoej.d kwrote:

shapper wrote:

I have two nullable DateTime: begin and end.
I need to find the range, in month, between both variables.

>

If for some reason, for example begin is null, it is not possible to
calculate the range then I want to define the range as 1 month.

>

How can I do this?

>
I don't think there are any magic.
>
if(dt1 != null && dt2 != null)
{
     delta = (dt2 - dt1).TotalMonth s;}
>
else
{
     delta = 1;
>
}
>
or something similar.
>
Arne

Arne,

There isn't a TotalMonths in TimeSpan ... only TotalDays, TotalHours,
TotalSeconds, TotalMinutes and TotalMilisecond s.

That was the first thing I looked.

Thanks,
Miguel

[Peter Duniho]

Re: DateTime range

On Sat, 18 Oct 2008 12:14:03 -0700, shapper <mdmoura@gmail. comwrote:

But does not my code calculate the difference between two dates in
months?

It does appear to, yes. But so does the code that Arne posted. And his
also addresses the specific question you actually asked. More
importantly, your code has a whole lot of math in it, whereas just using
the already-overloaded operator- as Arne suggests, you let the DateTime
type do all the work for you.

int diff = 12 * (begin.Year - end.Year) + begin.Month - end.Month;
int months = Math.Abs(diff);
>
I didn't address the nullable DateTime yet.

No, you didn't. But that's actually the question you appeared to have
asked. A solution that doesn't take into account null values isn't a
solution at all.

DateDiff, in my opinion, just creates an "easier" way to calculate
datetime spans in various intervals ...

What could be easier that just subtracting one DateTime from another?

Pete

[shapper]

Re: DateTime range

On Oct 18, 8:17 pm, "Peter Duniho" <NpOeStPe...@nn owslpianmk.com>
wrote:

On Sat, 18 Oct 2008 12:14:03 -0700, shapper <mdmo...@gmail. comwrote:

But does not my code calculate the difference between two dates in
months?

>
It does appear to, yes.  But so does the code that Arne posted.  And his  
also addresses the specific question you actually asked.  More  
importantly, your code has a whole lot of math in it, whereas just using  
the already-overloaded operator- as Arne suggests, you let the DateTime  
type do all the work for you.
>

int diff = 12 * (begin.Year - end.Year) + begin.Month - end.Month;
int months = Math.Abs(diff);

>

I didn't address the nullable DateTime yet.

>
No, you didn't.  But that's actually the question you appeared to have  
asked.  A solution that doesn't take into account null values isn't a  
solution at all.
>

DateDiff, in my opinion, just creates an "easier" way to calculate
datetime spans in various intervals ...

>
What could be easier that just subtracting one DateTime from another?
>
Pete

Arne code does not solve it ... It is used TotalMonths which does not
exist in C#. I could use TotalDays / 30 but that wouldn't be accurate.
That is the reason of my code ...

Or maybe as follows:

public static long DateSpan(DateIn terval interval, DateTime from,
DateTime to) {

// Define span
TimeSpan span = from - to;

// Check interval
switch (interval) {
case DateInterval.Ye ar:
return to.Year - from.Year;
case DateInterval.Mo nth:
return (to.Month - from.Month) + (12 * (to.Year -
from.Year));
case DateInterval.We ekday:
return CorrectDateSpan (span.TotalDays ) / 7;
case DateInterval.Da y:
return CorrectDateSpan (span.TotalDays );
case DateInterval.Ho ur:
return CorrectDateSpan (span.TotalHour s);
case DateInterval.Mi nute:
return CorrectDateSpan (span.TotalMinu tes);
default:
return CorrectDateSpan (span.TotalSeco nds);
}

} // DateSpan

private static long CorrectDateSpan (double number) {

if (number >= 0) {
return (long)Math.Floo r(number);
}
return (long)Math.Ceil ing(number);

} // CorrectDateSpan

Note: Didn't tested it yet ...

This function would be a good help specially when I am using this on a
Linq query to define some statistics.

I could include on my function an option that when one of the dates is
null or if from is after to I would return null and then I could set a
default value on my code where I am using the function.

[=?ISO-8859-1?Q?Arne_Vajh=F8j?=]

Re: DateTime range

shapper wrote:

On Oct 18, 6:40 pm, Arne Vajhøj <a...@vajhoej.d kwrote:

>shapper wrote:

>>I have two nullable DateTime: begin and end.
>>I need to find the range, in month, between both variables.
>>If for some reason, for example begin is null, it is not possible to
>>calculate the range then I want to define the range as 1 month.
>>How can I do this?

>I don't think there are any magic.
>>
>if(dt1 != null && dt2 != null)
>{
> delta = (dt2 - dt1).TotalMonth s;}
>>
>else
>{
> delta = 1;
>>
>}
>>
>or something similar.

There isn't a TotalMonths in TimeSpan ... only TotalDays, TotalHours,
TotalSeconds, TotalMinutes and TotalMilisecond s.
>
That was the first thing I looked.

Interesting.

It could be because TotalMonths is not very well defined.

Arne

[Peter Duniho]

Re: DateTime range

On Sat, 18 Oct 2008 12:32:51 -0700, shapper <mdmoura@gmail. comwrote:

Arne code does not solve it ... It is used TotalMonths which does not
exist in C#. I could use TotalDays / 30 but that wouldn't be accurate.
That is the reason of my code ...

Ah, right. Sorry. I just assumed that Arne wouldn't post code that
doesn't compile; that's more like me to do that, not him. :)

And yes, you're right...no TotalMonths for TimeSpan. Which actually makes
sense, now that I think about it, since TimeSpan is not relative to any
specific date, and the total months for a TimeSpan would depend on the
specific date.

My recollection is that the System.Globaliz ation.Calendar class has some
date/time math functionality in it. Whether it addresses this specific
question, I'm not sure, and I don't have time to check at the moment. But
you might look at that in the meantime.

You could certainly write the basics yourself, especially if you have only
a very narrow need (for example, you always know you only need months).
But if there's something in the framework that accomplishes it, that's
probably better. For that matter, if the Calendar class doesn't work,
maybe referencing the VB assembly is the best solution after all (but it
still won't deal with the nulls :p ...I really did read your original
question as being focused on the question of dealing with null values; I
didn't realize you were asking about the month calculation too).

Pete

[=?ISO-8859-1?Q?Arne_Vajh=F8j?=]

Re: DateTime range

shapper wrote:

On Oct 18, 8:17 pm, "Peter Duniho" <NpOeStPe...@nn owslpianmk.com>
wrote:

>On Sat, 18 Oct 2008 12:14:03 -0700, shapper <mdmo...@gmail. comwrote:

>>But does not my code calculate the difference between two dates in
>>months?

>It does appear to, yes. But so does the code that Arne posted. And his
>also addresses the specific question you actually asked. More
>importantly, your code has a whole lot of math in it, whereas just using
>the already-overloaded operator- as Arne suggests, you let the DateTime
>type do all the work for you.
>>

>>int diff = 12 * (begin.Year - end.Year) + begin.Month - end.Month;
>>int months = Math.Abs(diff);
>>I didn't address the nullable DateTime yet.

>No, you didn't. But that's actually the question you appeared to have
>asked. A solution that doesn't take into account null values isn't a
>solution at all.
>>

>>DateDiff, in my opinion, just creates an "easier" way to calculate
>>datetime spans in various intervals ...

>What could be easier that just subtracting one DateTime from another?

>
Arne code does not solve it ... It is used TotalMonths which does not
exist in C#.

Yep. Sorry about that.

I could use TotalDays / 30 but that wouldn't be accurate.
That is the reason of my code ...
>
Or maybe as follows:
>
public static long DateSpan(DateIn terval interval, DateTime from,
DateTime to) {
>
// Define span
TimeSpan span = from - to;
>
// Check interval
switch (interval) {
case DateInterval.Ye ar:
return to.Year - from.Year;
case DateInterval.Mo nth:
return (to.Month - from.Month) + (12 * (to.Year -
from.Year));

If that is the business logic you want, then that is probably
the way to go.

It is not obvious though that there are 1 months between September
30th and Octobet 1st but 0 months between October 1st and October 31st.

Arne

[shapper]

Re: DateTime range

On Oct 18, 8:41 pm, "Peter Duniho" <NpOeStPe...@nn owslpianmk.com>
wrote:

On Sat, 18 Oct 2008 12:32:51 -0700, shapper <mdmo...@gmail. comwrote:

Arne code does not solve it ... It is used TotalMonths which does not
exist in C#. I could use TotalDays / 30 but that wouldn't be accurate.
That is the reason of my code ...

>
Ah, right.  Sorry.  I just assumed that Arne wouldn't post code that  
doesn't compile; that's more like me to do that, not him.  :)
>
And yes, you're right...no TotalMonths for TimeSpan.  Which actually makes  
sense, now that I think about it, since TimeSpan is not relative to any  
specific date, and the total months for a TimeSpan would depend on the  
specific date.
>
My recollection is that the System.Globaliz ation.Calendar class has some  
date/time math functionality in it.  Whether it addresses this specific 
question, I'm not sure, and I don't have time to check at the moment.  But  
you might look at that in the meantime.
>
You could certainly write the basics yourself, especially if you have only  
a very narrow need (for example, you always know you only need months).  
But if there's something in the framework that accomplishes it, that's  
probably better.  For that matter, if the Calendar class doesn't work,  
maybe referencing the VB assembly is the best solution after all (but it  
still won't deal with the nulls :p ...I really did read your original  
question as being focused on the question of dealing with null values; I  
didn't realize you were asking about the month calculation too).
>
Pete

Thanks Pete. I will take a look into System.Globaliz ation.Calendar.

[shapper]

Re: DateTime range

On Oct 18, 8:42 pm, Arne Vajhøj <a...@vajhoej.d kwrote:

shapper wrote:

On Oct 18, 8:17 pm, "Peter Duniho" <NpOeStPe...@nn owslpianmk.com>
wrote:

On Sat, 18 Oct 2008 12:14:03 -0700, shapper <mdmo...@gmail. comwrote:
>But does not my code calculate the difference between two dates in
>months?
It does appear to, yes.  But so does the code that Arne posted.  And his  
also addresses the specific question you actually asked.  More  
importantly, your code has a whole lot of math in it, whereas just using  
the already-overloaded operator- as Arne suggests, you let the DateTime  
type do all the work for you.

>

>int diff = 12 * (begin.Year - end.Year) + begin.Month - end.Month;
>int months = Math.Abs(diff);
>I didn't address the nullable DateTime yet.
No, you didn't.  But that's actually the question you appeared to have  
asked.  A solution that doesn't take into account null values isn't a  
solution at all.

>

>DateDiff, in my opinion, just creates an "easier" way to calculate
>datetime spans in various intervals ...
What could be easier that just subtracting one DateTime from another?

>

Arne code does not solve it ... It is used TotalMonths which does not
exist in C#.

>
Yep. Sorry about that.
>
>
>

             I could use TotalDays / 30 but that wouldn'tbe accurate.
That is the reason of my code ...

>

Or maybe as follows:

>

    public static long DateSpan(DateIn terval interval, DateTime from,
DateTime to) {

>

      // Define span
      TimeSpan span = from - to;

>

      // Check interval
      switch (interval) {
        case DateInterval.Ye ar:
          return to.Year - from.Year;
        case DateInterval.Mo nth:
          return (to.Month - from.Month) + (12 * (to.Year -
from.Year));

>
If that is the business logic you want, then that is probably
the way to go.
>
It is not obvious though that there are 1 months between September
30th and Octobet 1st but 0 months between October 1st and October 31st.
>
Arne

Yes, I didn't test it completely but I will check that. But has far as
I know that is also how it works in VB's DateDiff.

[Todd Carnes]

Re: DateTime range

"shapper" <mdmoura@gmail. comwrote in message
news:5acdfe69-5d57-442e-aa52-b379f1266958@79 g2000hsk.google groups.com...
On Oct 18, 8:03 pm, "Peter Duniho" <NpOeStPe...@nn owslpianmk.com>
wrote:

Sorry Pete,
>
But does not my code calculate the difference between two dates in
months?

Arne's did that for you...plus it was much easier to read and follow.

Todd

[Jeff Johnson]

Re: DateTime range

"shapper" <mdmoura@gmail. comwrote in message
news:c6cd2f96-b6c3-4b55-a755-a6237dfa84e9@e1 7g2000hsg.googl egroups.com...

Arne code does not solve it ... It is used TotalMonths which does not
exist in C#.

I just want to point out that it has nothing to do with C#. TotalMonths is
not a property of the DateTime class, which belongs to the .NET Framework,
not C#.