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C# Static DictionaryDevelop a static Dictionary that tests strings. Compute plural words from singular words.
Static Dictionary. A static Dictionary can store global data. It lets you quickly look up strings (or other values). It is shared among many instances.
Static info. A static Dictionary, existing only once in memory, is efficient. We can store values in one location, and access them from many methods.
Dictionary
Static
Simple example. Let us begin with a simple example that shows the mechanics of using a static Dictionary. We can access the static "gems" dictionary in both Main, and the Test() method.
C# program that uses static Dictionary
using System; using System.Collections.Generic; class Program { static Dictionary<string, int> _gems = new Dictionary<string, int>(); static void Main() { // Add some data to static dictionary. _gems.Add("diamond", 500); _gems.Add("ruby", 200); // Call another method. Test(); } static void Test() { // Use static dictionary. _gems.TryGetValue("diamond", out int value); Console.WriteLine("STATIC DICTIONARY RESULT: {0}", value); } }
STATIC DICTIONARY RESULT: 500
Complex example. The example here is useful code for finding a plural version of a word. You can pass in a string, and the method will return the pluralized version.
Static The Dictionary doesn't need to be created in multiple instances. Only one instance is needed.
GetPlural Access to the string keys and values is provided through the public method GetPlural.
Public, private
Example This code will return the value in the static Dictionary that is found at the key specified.
C# program that uses static Dictionary
using System; using System.Collections.Generic; class Program { static void Main() { // Write plural words from static Dictionary. var result = PluralStatic.GetPlural("game"); Console.WriteLine("RESULT: {0}", result); } } /// <summary> /// Contains plural logic in static class [separate file] /// </summary> static class PluralStatic { /// <summary> /// Static string Dictionary example /// </summary> static Dictionary<string, string> _dict = new Dictionary<string, string> { {"entry", "entries"}, {"image", "images"}, {"view", "views"}, {"file", "files"}, {"result", "results"}, {"word", "words"}, {"definition", "definitions"}, {"item", "items"}, {"megabyte", "megabytes"}, {"game", "games"} }; /// <summary> /// Access the Dictionary from external sources /// </summary> public static string GetPlural(string word) { // Get the result from the static Dictionary. string result; if (_dict.TryGetValue(word, out result)) { return result; } else { return null; } } }
RESULT: games
Notes, storage. A static Dictionary can be stored in a non-static class. In this case, it will still be tied to the type, not the instance. A static Dictionary can improve performance.
Tip If one dictionary can be shared among many class instances, often performance will improve.
A summary. Static Dictionaries can store global program data. We saw example code that encapsulates a static Dictionary in a class, which is instantiated only once in the entire program.
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