1. MIS 324 -- Professor Sandvig MIS 324 Professor Sandvig
2/24/2019
C# Collections
MIS 324
Professor Sandvig

2. Overview What are collections Arrays Language Integrated Query (LINQ)
Sort & filter collections
Similar to SQL
Generic List<>

3. What are Collections Collections store multiple data values
Frequently work with collections:
Database records
List of products
List of people
Shopping cart
Cookies
Web form values
Etc.

4. What Are Collections Arrays .NET library namespaces
C# feature
Simple
Limited functionality
.NET library namespaces
System.Collections
System.Collections.Generic
Classes for managing collections of data

5. What are Collections
Select collection type based on desired behavior & performance
Many choices:
Array
Queue
Stack
Dictionary
List<>
Sorted List
Etc.

6. What are Collections A few types of collections: Collection Best for
Dictionary
Fast lookups
Sorted list
Items sorted on Insert
List
General use
Stack
Last in First Out (LIFO)
Queue
First in First Out (FIFO)

7. Array Simple collection type Basic C# language feature
Limited features
No sorting
No filtering
Limited to C# data types

8. Array Advantages Disadvantages Simple Basic features:
Iterate, retrieve values, find value
Disadvantages
Limited to C# data types
String, Int, Double, etc.
Size fixed when initialized

9. Collections Namespaces
.NET library namespaces
System.Collections
System.Collections.Generic
Provide classes for managing data
Lookup (fast)
Sort
Filter
Find
Etc.

10. Generic Collections System.Collections.Generic namespace
Strongly typed!
Faster
Used extensively in MVC
Retain datatypes defined in model
.NET Library
Documentation

11. Generic Collections Why “generic”? Declare type when create collection
Items in collection can be any “generic” object
Declare type when create collection
List<int> myGenericList = new List<int>();
Generics can hold any object
List<PersonModel> personList = new List<PersonModel>();
See code sample

12. MIS 324 -- Professor Sandvig
2/24/2019
Generic List<>
List<> only collection used in MIS 324
Used in ViewModels
Fonts
States
List<> has methods for sorting, finding, etc.
Often use LINQ (Language Integrated Query) to query List

13. LINQ Language Integrated Query Query language built into C#
Use with any collection type
Including database
Capabilities similar to SQL
Uses Lamda Syntax
.where(collection => expression)
Collection Examples

14. Summary Collections frequently used Generic Collections Strongly typed
Generic List<> used for most data lists