Re: My First C# (warning - long post)

"andrewmcdonagh" <andrewmcdonagh@gmail.com> wrote in message
news:1170416819.673830.134600@k78g2000cwa.googlegroups.com...
> On Feb 2, 1:42 am, LX-i <lxi0...@netscape.net> wrote: 
<snip>

> Quick suggestion about your COBOL keywords....  instead of using an
> XML file, or raw array, you'll get much better (near constant time)
> lookup performance if you use a single in memory HashTable collection.
> Hashtables use two objects, one is a 'key' and the other a 'value'.
> Unfortunately the c# library doesn't have a Java HashSet, which has
> the same behaviour as hastables, but is for storing keys only.
>
Er...not necessarily... :-)

Although C# supports the Hashtable function (so Java folks can remain
comfortable...:-)),  it is much better to use the C# Dictionary Class
because it doesn't require boxing and unboxing of objects.

Furthermore, the Dictionary Class DOES support a collection of Keys and
Values as separate entities, if you want this.

I have no issue with the approach (it's very good), but would strongly
recommend Dictionary, rather than Hashtable.

(Check out the VS 2005 Help index for "Dictionary"...)

> // Create a new hash table.
> Hashtable cobolKeywords = new Hashtable();
>
> // Add some elements to the hash table.
> // hashtable does not allow
> // duplicate keys, but values can be duplicates.
> cobolKeywords.Add("ACCEPT", "ACCEPT ");
> cobolKeywords.Add("ACCESS", "ACCESS");
> cobolKeywords.Add("ACQUIRE", "ACQUIRE");
> cobolKeywords.Add("ADD", "ADD");
> ...
>
>  // The Item property is the default property, so you
>  // can omit its name when accessing elements.
>  Console.WriteLine("The value for Add = ", cobolKeywords["ADD"]   );
>
>  // ContainsKey can be used to test keys before inserting them.
>  if (! cobolKeywords.ContainsKey("BEFORE"))
>  {
>     cobolKeywords.Add("BEFORE", "BEFORE");
>     Console.WriteLine("Value added for key = \"ht\": {0}",
> cobolKeywords["ht"]);
>  }
>
>  // When you use foreach to enumerate hash table elements,
>  // the elements are retrieved as KeyValuePair objects.
>
>  foreach( DictionaryEntry de in cobolKeywords)
>  {
>      Console.WriteLine("Key = {0}, Value = {1}", de.Key, de.Value);
>  }
>
>   // To get the values alone, use the Values property.
>   ICollection valueColl = cobolKeywords.Values;
>
>   // The elements of the ValueCollection are strongly typed
>   // with the type that was specified for hash table values.
>
>   foreach( string s in valueColl )
>   {
>         Console.WriteLine("Value = {0}", s);
>   }
>

Really good sample code above, Andrew. Good stuff!

Pete.