Had a project where we needed to be able to process items in a list in random order. The implementation of the random order was a little verbose. This extension method on IList<T> works pretty well for me.
static readonly Random _random = new();
/// <summary>
/// This is a Shuffle extension to shuffle the order of Lists randomly
/// </summary>
/// <typeparam name="T"><typeparam>
/// <param name="list"></param>
public static void Shuffle<T>(this IList<T> list)
{
int intListCount = list.Count;
while (intListCount > 1)
{
intListCount--;
int intRandom = _random.Next(intListCount + 1);
T value = list[intRandom];
list[intRandom] = list[intListCount];
list[intListCount] = value;
}
}
The above sample uses the System.Random implementation to retrieve a random number by passing in the count of the list + 1. The reason I’m adding 1 here is because the Next method is zero (0) based, so it will return a number from 0 to your list count – 1. There is another overload that you can pass in the starting value and the ending value.
int intRandom = _random.Next(1, intListCount);
So this extension method will shuffle your list and give you back a list that is in random order each time.
If you’d like to see more extension methods, take a look at my post Jack’s Top 10 String Extension Methods
Related
Author: Jack Yasgar
Jack Yasgar has been developing software for various industries for two decades. Currently, he utilizes C#, JQuery, JavaScript, SQL Server with stored procedures and/or Entity Framework to produce MVC responsive web sites that converse to a service layer utilizing RESTful API in Web API 2.0 or Microsoft WCF web services. The infrastructure can be internal, shared or reside in Azure.
Jack has designed dozens of relational databases that use the proper primary keys and foreign keys to allow for data integrity moving forward.
While working in a Scrum/Agile environment, he is a firm believer that quality software comes from quality planning. Without getting caught up in analysis paralysis, it is still possible to achieve a level of design that allows an agile team to move forward quickly while keeping re-work to a minimum.
Jack believes, “The key to long term software success is adhering to the SOLID design principles. Software written quickly, using wizards and other methods can impress the business sponsor / product owner for a short period of time. Once the honeymoon is over, the product owner will stay enamored when the team can implement changes quickly and fix bugs in minutes, not hours or days.”
Jack has become certified by the Object Management Group as OCUP II (OMG Certified UML Professional) in addition to his certification as a Microsoft Certified Professional. The use of the Unified Modeling Language (UML) provides a visual guide to Use Cases and Activities that can guide the product owner in designing software that meets the end user needs. The software development teams then use the same drawings to create their Unit Tests to make sure that the software meets all those needs.
The QA testing team can use the UML drawings as a guide to produce test cases. Once the software is in production, the UML drawings become a reference for business users and support staff to know what decisions are happening behind the scenes to guide their support efforts.
View all posts by Jack Yasgar
