Interesting C# puzzle

[JV]

I have 3 string values that I want to perform a range comparison on:

string minValue = "1050";
string maxValue = "5300";
string theValue = "3239";

I have another string that tells me the type I need to convert the above
strings to before comparing:

string convertToType = "int";

The code cannot assume anything about the above values or the type that it
must convert to for the comparison, except that the type is a supported type
in C#. So, logically you would do something like:

object oMin = Convert.ChangeType(minValue, Type.GetType(convertToType));
// etc. giving you 3 object variables which are actually of type int

The problem is the comparison. You can't do the following because object
does not support the operators:

bool isInRange = (oValue >= oMin) && (oValue <= oMax);

So, other than creating a giant switch() statement with a case for each
possible type you care to support, how would you go about performing the
above comparison?

[Jon Skeet [C# MVP]]

JV <oy********@spammenot.com> wrote:

<snip>

The problem is the comparison. You can't do the following because object
does not support the operators:

bool isInRange = (oValue >= oMin) && (oValue <= oMax);

So, other than creating a giant switch() statement with a case for each
possible type you care to support, how would you go about performing the
above comparison?

I'd assume that the types involved implemented IComparable, and use
that after doing the conversion. Indeed, comparisons without advance
knowledge of the types involved is precisely what the IComparable
interface is for :)

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[Luc E. Mistiaen]

if you are sure that the type where you convert is IComparable you can do

IComparable cVal = (IComparable) oVal;
if (cVal.CompareTo(oMin) < 0) do something etc...

if you are not sure, you protect the construct in a try/catch.

/LM

"JV" <oy********@spammenot.com> wrote in message
news:%2****************@TK2MSFTNGP02.phx.gbl...

I have 3 string values that I want to perform a range comparison on:

string minValue = "1050";
string maxValue = "5300";
string theValue = "3239";

I have another string that tells me the type I need to convert the above
strings to before comparing:

string convertToType = "int";

The code cannot assume anything about the above values or the type that it
must convert to for the comparison, except that the type is a supported
type in C#. So, logically you would do something like:

object oMin = Convert.ChangeType(minValue, Type.GetType(convertToType));
// etc. giving you 3 object variables which are actually of type int

The problem is the comparison. You can't do the following because object
does not support the operators:

bool isInRange = (oValue >= oMin) && (oValue <= oMax);

So, other than creating a giant switch() statement with a case for each
possible type you care to support, how would you go about performing the
above comparison?

[clintonG]

Uh, isn't it kind of dumb not to use an int in the first place?

--
<%= Clinton Gallagher
NET csgallagher AT metromilwaukee.com
URL http://clintongallagher.metromilwaukee.com/


"JV" <oy********@spammenot.com> wrote in message
news:%2****************@TK2MSFTNGP02.phx.gbl...

I have 3 string values that I want to perform a range comparison on:

string minValue = "1050";
string maxValue = "5300";
string theValue = "3239";

I have another string that tells me the type I need to convert the above
strings to before comparing:

string convertToType = "int";

The code cannot assume anything about the above values or the type that it
must convert to for the comparison, except that the type is a supported
type in C#. So, logically you would do something like:

object oMin = Convert.ChangeType(minValue, Type.GetType(convertToType));
// etc. giving you 3 object variables which are actually of type int

The problem is the comparison. You can't do the following because object
does not support the operators:

bool isInRange = (oValue >= oMin) && (oValue <= oMax);

So, other than creating a giant switch() statement with a case for each
possible type you care to support, how would you go about performing the
above comparison?

[Michael C]

"Luc E. Mistiaen" <lu**********@advalvas.be.no.spam> wrote in message
news:ee**************@TK2MSFTNGP05.phx.gbl...

if you are sure that the type where you convert is IComparable you can do

IComparable cVal = (IComparable) oVal;
if (cVal.CompareTo(oMin) < 0) do something etc...

if you are not sure, you protect the construct in a try/catch.

Or provide a switch statement for those that aren't IComparable.

Michael

[JV]

Well, no it's not dumb. I just didn't give you the full context of the
problem. But, in this case it involves a string field containing candidate
key information which sometimes is all numeric and sometimes is not. The
rules being processed are pretty complex.
"clintonG" <cs*********@REMOVETHISTEXTmetromilwaukee.com> wrote

Uh, isn't it kind of dumb not to use an int in the first place?

--
<%= Clinton Gallagher
NET csgallagher AT metromilwaukee.com
URL http://clintongallagher.metromilwaukee.com/

[JV]

Thanks. I knew there had to be an interface that value types implemented.
I just wasn't quite sure how to go about finding out what it was.

I suppose I could also use the "is" operator rather than try/catch.

"Luc E. Mistiaen" <lu**********@advalvas.be.no.spam> wrote in message
news:ee**************@TK2MSFTNGP05.phx.gbl...

if you are sure that the type where you convert is IComparable you can do

IComparable cVal = (IComparable) oVal;
if (cVal.CompareTo(oMin) < 0) do something etc...

if you are not sure, you protect the construct in a try/catch.

/LM

"JV" <oy********@spammenot.com> wrote in message
news:%2****************@TK2MSFTNGP02.phx.gbl...

I have 3 string values that I want to perform a range comparison on:

string minValue = "1050";
string maxValue = "5300";
string theValue = "3239";

I have another string that tells me the type I need to convert the above
strings to before comparing:

string convertToType = "int";

The code cannot assume anything about the above values or the type that
it must convert to for the comparison, except that the type is a
supported type in C#. So, logically you would do something like:

object oMin = Convert.ChangeType(minValue, Type.GetType(convertToType));
// etc. giving you 3 object variables which are actually of type int

The problem is the comparison. You can't do the following because object
does not support the operators:

bool isInRange = (oValue >= oMin) && (oValue <= oMax);

So, other than creating a giant switch() statement with a case for each
possible type you care to support, how would you go about performing the
above comparison?

[Luc E. Mistiaen]

> I suppose I could also use the "is" operator rather than try/catch.

Of course. I just thought this was a case that was not supposed to happen,
in which case exception are probably clearer.

/LM

[Kevin Spencer]

> I suppose I could also use the "is" operator rather than try/catch.

But wouldn't that depend on what your definition of "is" is?

And what you do when you try and get caught?

--
Sorry, couldn't help myself,

Kevin Spencer
Microsoft MVP
Professional Numbskull

Hard work is a medication for which
there is no placebo.

"JV" <oy********@spammenot.com> wrote in message
news:%2****************@TK2MSFTNGP03.phx.gbl...

Thanks. I knew there had to be an interface that value types implemented.
I just wasn't quite sure how to go about finding out what it was.

I suppose I could also use the "is" operator rather than try/catch.

<snip>

[Rene]

You should be aware that comparing string using IComparable is not the best
thing to do because you are not explicitly indicating how the strings are
compared.

The default CompareTo performs a culture-Sensitive comparation (I believe
base on the thread culture info). This could cause you problems if your
application is being used in multiples countries.

Just a heads up note.
"JV" <oy********@spammenot.com> wrote in message
news:%2****************@TK2MSFTNGP02.phx.gbl...

I have 3 string values that I want to perform a range comparison on:

string minValue = "1050";
string maxValue = "5300";
string theValue = "3239";

I have another string that tells me the type I need to convert the above
strings to before comparing:

string convertToType = "int";

The code cannot assume anything about the above values or the type that it
must convert to for the comparison, except that the type is a supported
type in C#. So, logically you would do something like:

object oMin = Convert.ChangeType(minValue, Type.GetType(convertToType));
// etc. giving you 3 object variables which are actually of type int

The problem is the comparison. You can't do the following because object
does not support the operators:

bool isInRange = (oValue >= oMin) && (oValue <= oMax);

So, other than creating a giant switch() statement with a case for each
possible type you care to support, how would you go about performing the
above comparison?

[james.curran]

The data types are your friends. Don't try to fight them.

switch(convertToType)
{
case "int";
int iMinValue = Convert.ToInt32(minValue);
int iMaxValue = Convert.ToInt32(maxValue):
int iValue = Convert.ToInt32(theValue)
bool isInRange = (iValue >= iMin) && (iValue <= oMax);
break;

case "string":
// etc.

}