CODEWITHSUNDEEP
c#listindexing
zetar
zetar

Reputation: 1233

Getting the index of a list from a string in another list

I have two lists:

public static List<Dinosaur> Dinosaurs = new List<Dinosaur>();
public static List<DinosaurSpecies> DinosaurSpeciesList = new List<DinosaurSpecies>();

I want to use the Species in the first list to find the key of the Species in the second list. The following throws a 'has some invalid arguments' but it does illustrate what I'm trying to do:

int index = MainWindow.DinosaurSpeciesList.FindIndex(MainWindow.Dinosaurs[i].Specie);

In other words, where does the Species in the Dinosaurs list [index] appear in the list of all DinosaurSpecies?

Upvotes: 1

Views: 143

Answers (2)

musefan
musefan

Reputation: 48415

You can do this by passing a predicate to the FindIndex method:

int index = MainWindow.DinosaurSpeciesList.FindIndex(x => x.Specie == MainWindow.Dinosaurs[i].Specie);

Basically, you are saying: Find the index of the element whos Specie property is equal to the specified Dinosaur.Specie property

A simplified and more understandable example might be:

Dinosaur dinosaur = GetDinosaurToFindSpeciesInformationFor();
int index = DinosaurSpeciesList.FindIndex(x => x.Specie == dinosaur.Specie);

Of course, if you then plan to only use the index to get the DinosaurSpecies object anyway, you could do this:

DinosaurSpecies species = DinosaurSpeciesList.SingleOrDefault(x => x.Specie == dinosaur.Specie);
//NOTE: species will be null if there are no matches, or more than one match

Upvotes: 3

kenchilada
kenchilada

Reputation: 7559

Your parameters to FindIndex are wrong. The single-parameter form requires a lambda (or more specifically, a Predicate<T>):

int index = MainWindow.DinosaurSpeciesList.FindIndex(x => x.Specie.Equals(MainWindow.Dinosaurs[i].Specie));

Depending on what your DinosaurSpecies class looks like, of course.

ps. I like dinosaurs

Upvotes: 2

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