Coding 101

Sep 25th 2014

Coding 101 36

C# Collections

Lists, arrays, dictionaries, and hashes.
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Guests: Louis Maresca
Category: Help & How To

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Snubs Compiled

Thanks to Joe Maruschek for showing us why the MVVM pattern works so well!

Ivory Tower

Lists & Array (Dictionary, Hash) Collections * Often, we want to create and manage groups of objects that are related to each other in some way. The .NET Framework gives us classes that have been specifically designed for data storage and retrieval. Arrays are fine when we are working with a FIXED number of uniformly typed objects -- But they don't work so well when we start working with an indeterminate number of objects, or with objects that are not strongly typed. Unlike Arrays, the group of objects with a COLLECTION can grow and shrink DYNAMICALLY. ** To use Collections, we add the Include: "using System.Collections;" Arrays * An Array is a way to store values within an "object" that uses a single identifer with an "index" value to point to an particular value within the index * n.b --- An array is an OBJECT. * In C#, arrays can be fixed or dynamic -- You can set the LENGTH of the array -- OR you can make it of an undetermined size. Dynamic Array int[] TWiTArray; * This will create a DYNAMIC array of Integers called "TWiTArray" of an undetermined length Static Array "int[] C101Array; C101Array = new int[100];" This creates a FIXED array of integers called "C101Array" with 100 values, from 0 to 99 But it Doesn't have to be Integer Values double, char bool, string --- these are all types of arrays you can make. Lists * A "List" is an array that can be dynamically resized. -- This means that you don't need to determine how big the dataset will eventually be -- The list will automatically grow as you add more values. Dictionaries: * Dictionaries let us create objects with elements that are searchable by keys Hash: * A Hashtable allow us to look up elements via their hashes.

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