Right now I have a const array of strings and loop through to check if a value exists. But I want a more efficient way to store my values. I know there's a hashset which I can use like so:
HashSet<string> tblNames = new HashSet<string> ();
tblNames.Add("a");
tblNames.Add("b");
tblNames.Add("c");
However, is it possible to make this a constant member of my class like this:
public const HashSet<string> tblNames = new HashSet<string>() { "value1", "value2" };
The best way to create a 'constant' Set is probably by exposing your HashSet as its IEnumerable interface, using the following:
public static readonly IEnumerable<string> fruits = new HashSet<string> { "Apples", "Oranges" };
public: everyone can access it.static: there's only going to be one copy in memory, no matter how many instances of the parent class is created.readonly: you can't re-assign it to a new value.IEnumerable<>: you can only iterate through its contents, but not add/remove/modify.To search, you can use LINQ to call Contains() on your IEnumerable, and it is smart enough to know it's backed by a HashSet and delegate the proper call to utilise the hashed nature of your set. (well, ok, it calls it via ICollection, but ends up in HashSet's overridden method anyway)
Debug.WriteLine(fruits.Contains("Apples")); // True
Debug.WriteLine(fruits.Contains("Berries")); // False
fruits = new HashSet<string>(); // FAIL! readonly fields can't be re-assigned
fruits.Add("Grapes"); // FAIL! IEnumerables don't have Add()
and it is smart enough to know it's backed by a HashSet and delegate the proper call to utilise the hashed nature of your set. (well, ok, it calls it via ICollection, but ends up in HashSet's overridden method anyway) IEnumerable and ICollection are simply interfaces. They do not define default implementations for Contains(). When you call Contains() it will directly call the hashset implementation.
But I want a more efficient way to store my values.What do you mean bymore efficient?static readonlyrather thanconst. Alas, since it ispublicother code will be able to add or remove items from theHashSet.constquestions, as they don't address preventing the Set contents from being added/removed.HashSet<T>. There is anImmutableHashSet<T>class in the package System.Collections.Immutable.