Find object in list with specific value

Question

I have this class:

public class Person
{
    public String name;
    public int score;
    public float multiplier;

    public Person(String nameID)
    {
        name = nameID;
        score = 0;
        multiplier = 1.0f;
    }
}

And I have a List containing these classes:

private List<Person> _people;

Is there some way I could get a score using a name, like this?

_people.GetScore("example name"); // return the score of the class containing that name?

Possible duplicate of [Filtering collections in C#](https://stackoverflow.com/questions/26196/filtering-collections-in-c-sharp) — Nisarg Shah, Feb 26 '18 at 07:26

Salah Akbari · Accepted Answer · 2018-02-26T12:07:10.740

8

Use LINQ:

_people.FirstOrDefault(c => c.name == "example name")?.score;

Just don't forget to add using System.Linq; to your using directives first. Also note that you need to use Null-conditional operator(?.) also, that is used to test for null before performing a member access (score in this case) Also it would be better to use properties instead of fields:

public string Name { get; set; }

edited Feb 26 '18 at 12:07

answered Feb 26 '18 at 07:23

Salah Akbari

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1

And if the name is not found in the list? – Rotem Feb 26 '18 at 07:25
1

@Rotem Thanks. Check my updated answer and `?` operator. – Salah Akbari Feb 26 '18 at 07:26
@S.Akbari Thanks, I'll look into Linq. I'm new to C#, what does the { get; set; } do? – James A Feb 26 '18 at 07:36
@JamesA They are Auto-Implemented Properties. Read this https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/auto-implemented-properties – Salah Akbari Feb 26 '18 at 07:37

Prasad Telkikar · Answer 2 · 2018-02-26T07:44:06.117

2

You can use linq query to get the result:

int result = _people.FirstOrDefault(p => p.name == "example name").score

If _people list contains multiple records with name "example name" then you can use where clause and get all results from the list

var results = _people.Where(p => p.name == "example name");
    foreach(var r in results)
        Console.WriteLine(r.score);

Now you can iterate through the results to get all scores

Here is the implementation: DotNetFiddler

edited Feb 26 '18 at 07:44

answered Feb 26 '18 at 07:23

Prasad Telkikar

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`Where` returns a filtered `IEnumerable`, not a single result. – Rotem Feb 26 '18 at 07:23
Thanks @Rotem, I made corrections to it. FirstOrDefault is more precise than where – Prasad Telkikar Feb 26 '18 at 07:25
@Rotem, I used `FirstOrDefault` as well as `Where` clause. Thanks for your suggestions – Prasad Telkikar Feb 26 '18 at 07:46

score -1 · Answer 3 · answered Feb 26 '18 at 07:22

-1

You can you Single method of IEnumerable

var score = _people.Single(p => p.name == "example name").score

answered Feb 26 '18 at 07:22

ema

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a `Single` methond can only be used if there is one and only one element in the sample by it's predicate – Nikolay Lebedev Feb 26 '18 at 07:28
I thought that `name` is a primary key for a Player. Can exist two player with the same name? – ema Feb 26 '18 at 17:03
Sometimes they can. So there may be no players with that name, because, for example, he has not yet appeared in the game. – Nikolay Lebedev Feb 26 '18 at 17:11

Find object in list with specific value

3 Answers3