C# Enums - Feature or deficiency

[Ian Semmel]

If I have

Enum en
{
i1,
i2,
i3
}

I reckon I should be able to have

int[] v = new int [ en ];

It is obvious what I want to do, but the compiler doesn't like it.

The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

[Stephany Young]

Well, seeing as how what you want to do is so obvious, maybe you'd like to
explain what you want to do so that we, who are obviously deficient in the
area of ESP, can get an idea.
"Ian Semmel" <an****@rocketc omp.com.auwrote in message
news:422B1F174E 5748EAAE0F2A995 E0ABD2B@DIMITY. ..

If I have

Enum en
{
i1,
i2,
i3
}

I reckon I should be able to have

int[] v = new int [ en ];

It is obvious what I want to do, but the compiler doesn't like it.

The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

[Chris Nahr]

On Sun, 9 Dec 2007 16:57:44 +1000, "Ian Semmel"
<an****@rocketc omp.com.auwrote :

>The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

Sadly, no. At least not in the general case. (Although you can use
Length instead of GetLength(0) which is a little bit shorter.)

In your particular case you could simply use (int) en.i3 + 1 because
the default base type of an enumeration is int (Int32) and values
start with zero, incrementing by one with each extra value.

But that requires changing your code whenever you add an enum value.
You could add an extra value, such as "last = i3", and use that
instead for array dimensioning etc. But you'd still have to remember
to update this "last" value when the enumeration changes.
--
http://www.kynosarges.de

[BobF]

"Ian Semmel" <an****@rocketc omp.com.auwrote in message
news:422B1F174E 5748EAAE0F2A995 E0ABD2B@DIMITY. ..

If I have

Enum en
{
i1,
i2,
i3
}

I reckon I should be able to have

int[] v = new int [ en ];

It is obvious what I want to do, but the compiler doesn't like it.

The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

I would do this (but I'm not a purest):

Enum en
{
i1,
i2,
i3,

enumLength
}

int[] v = new int[enumLength];

[=?ISO-8859-1?Q?Lasse_V=E5gs=E6ther_Karlsen?=]

Ian Semmel wrote:

If I have

Enum en
{
i1,
i2,
i3
}

I reckon I should be able to have

int[] v = new int [ en ];

It is obvious what I want to do, but the compiler doesn't like it.

The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

..NET arrays are indexed arrays, not associative arrays. The only way you
can index an array in .NET is through an integer, which is why the
compiler doesn't like you trying to use an enum as its index.

--
Lasse Vågsæther Karlsen
mailto:la***@vk arlsen.no
http://presentationmode.blogspot.com/

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

Ian Semmel wrote:

If I have

Enum en
{
i1,
i2,
i3
}

I reckon I should be able to have

int[] v = new int [ en ];

It is obvious what I want to do, but the compiler doesn't like it.

The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

C# is of the C++/Java family - you only specify number
of elements in the array N and array indexes are integers
0..N-1 !

Using types as an array index is a Pascal/Ada family
thing.

Arne

[Ian Semmel]

-----Original Message-----
From: BobF [mailto:rN****** *****@charter.n et]
Posted At: Sunday, 9 December 2007 10:31 PM
Posted To: microsoft.publi c.dotnet.langua ges.csharp
Conversation: C# Enums - Feature or deficiency
Subject: Re: C# Enums - Feature or deficiency
"Ian Semmel" <an****@rocketc omp.com.auwrote in message
news:422B1F174E 5748EAAE0F2A995 E0ABD2B@DIMITY. ..

If I have

Enum en
{
i1,
i2,
i3
}

I reckon I should be able to have

int[] v = new int [ en ];

It is obvious what I want to do, but the compiler doesn't like it.

The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

I would do this (but I'm not a purest):

Enum en
{
i1,
i2,
i3,

enumLength
}

int[] v = new int[enumLength];

Yes, that is the technique I use in C/C++. The reason is that it makes
programs self-resizing as if I add an i4, I don't have to change
anything else.

From other replies in the thread, it seems that C# doesn't allow enums
to be used as array indexes which to me seems like a hole in the
specification as the two are linked in my opinion.

[Ian Semmel]

-----Original Message-----
From: Arne Vajhøj [mailto:ar**@vaj hoej.dk]
Posted At: Monday, 10 December 2007 2:21 AM
Posted To: microsoft.publi c.dotnet.langua ges.csharp
Conversation: C# Enums - Feature or deficiency
Subject: Re: C# Enums - Feature or deficiency

Ian Semmel wrote:

If I have

Enum en
{
i1,
i2,
i3
}

I reckon I should be able to have

int[] v = new int [ en ];

It is obvious what I want to do, but the compiler doesn't like it.

The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

C# is of the C++/Java family - you only specify number
of elements in the array N and array indexes are integers
0..N-1 !

Using types as an array index is a Pascal/Ada family
thing.

Arne

Enums have always been the poor cousin in C/C++ and apparently C#.

[Ian Semmel]

>
Well, seeing as how what you want to do is so obvious, maybe you'd

like

to
explain what you want to do so that we, who are obviously deficient in
the
area of ESP, can get an idea.

A not uncommon thing I would have thought.

class enAttributes
{
string description;
int somethingelse;
}

enAttributes[] attr = new enAttributes [ en ];

enAttributes a1 = attr [ i1 ];

i1 has a value, I can't see why the compiler can't do the necessary
type-casting.

>

"Ian Semmel" <an****@rocketc omp.com.auwrote in message
news:422B1F174E 5748EAAE0F2A995 E0ABD2B@DIMITY. ..

If I have

Enum en
{
i1,
i2,
i3
}

I reckon I should be able to have

int[] v = new int [ en ];

It is obvious what I want to do, but the compiler doesn't like it.

The only way I know to do it is (is there a better way?)

v = new int[ Enum.GetValues( typeof ( en) ).GetLength (0) ];

[Jon Skeet [C# MVP]]

Ian Semmel <an****@rocketc omp.com.auwrote :

<snip>

enAttributes[] attr = new enAttributes [ en ];

enAttributes a1 = attr [ i1 ];

i1 has a value, I can't see why the compiler can't do the necessary
type-casting.

Because i1 is *not* an integer, it's an enum. If you want to create a
map from enum values to something else, use Dictionary<K,V> .

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
World class .NET training in the UK: http://iterativetraining.co.uk