Creating a case-insensitive Hashtable in v2

[Mark Rae]

Hi,

In v1.x, I used to use the following code to create a case-insensitive
Hashtable:

Hashtable MyHashtable = new
Hashtable(CaseInsensitiveHashCodeProvider.Default,
CaseInsensitiveComparer.Default);

In v2, this generates the following warnings:

Warning 1 'System.Collections.CaseInsensitiveHashCodeProvider' is obsolete:
'Please use StringComparer instead.
Warning 4
'System.Collections.Hashtable.Hashtable(System.Collections.IHashCodeProvider,
System.Collections.IComparer)' is obsolete: 'Please use
Hashtable(IEqualityComparer) instead.

However, when I go to the online Help for Hashtable, that's pretty much the
code it still suggests.

Can anyone please tell me the v2 way of creating a case-insensitive
Hashtable?

Any assistance gratefully received.

Mark

 

[Jon Skeet [C# MVP]]

In v1.x, I used to use the following code to create a case-insensitive
Hashtable:

Hashtable MyHashtable = new
Hashtable(CaseInsensitiveHashCodeProvider.Default,
CaseInsensitiveComparer.Default);

In v2, this generates the following warnings:

Warning 1 'System.Collections.CaseInsensitiveHashCodeProvider' is obsolete:
'Please use StringComparer instead.
Warning 4
'System.Collections.Hashtable.Hashtable(System.Collections.IHashCodeProvider,
System.Collections.IComparer)' is obsolete: 'Please use
Hashtable(IEqualityComparer) instead.

However, when I go to the online Help for Hashtable, that's pretty much the
code it still suggests.

Can anyone please tell me the v2 way of creating a case-insensitive
Hashtable?

Well, the preferred way of creating a map in 2.0 is usually to use
Dictionary<TKey, TValue>, passing in an IEqualityComparer<T>. In this
case, you would create a Dictionary<string,Foo> (where Foo is whatever
type your values are) and pass in an instance of StringComparer - eg
StringComparer.OrdinalIgnoreCase or
StringComparer.CurrentCultureIgnoreCase.

 

[Mark Rae]

Well, the preferred way of creating a map in 2.0

A map...???

is usually to use Dictionary<TKey, TValue>

So we don't use a Hashtable any more...?

 

[Jon Skeet [C# MVP]]

A map...???

A map from keys to values.

So we don't use a Hashtable any more...?

Not most of the time. Think of Dictionary<TKey, TValue> as a strongly-
typed version of Hashtable.

 

[Mark Rae]

A map from keys to values.

Oh right, I see now...

Not most of the time. Think of Dictionary<TKey, TValue> as a strongly-
typed version of Hashtable.

OK, thanks for that. I'm still getting to grips with v2, so that sort of
advice is particularly helpful.

 

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