first element of the listBox c#

Question

I just want to take the first element from a list and add it to a file. My problem is that I am not sure why the function "take" does not work, is not compiling because of it.

ListBox does not contain a definition for 'First' and no extension method 'First' accepting a first argument of type 'ListBox' could be found (are you missing a using directive or an assembly reference?

var firstItem = Ingredients.Take(1);

File.AppendAllText("Pizza.txt", firstItem + Environment.NewLine);

Why not `Inngredients.First()`? – Johnny Feb 22 '18 at 18:26 — Johnny, Feb 22 '18 at 18:26

Titian Cernicova-Dragomir · Accepted Answer · 2018-02-22T18:53:13.227

2

Take will create an IEnumerable with the number of elements that is specified as an argument. You are looking for First()

var firstItem = Ingredients.First();

File.AppendAllText("Pizza.txt", firstItem + Environment.NewLine);

If the list is empty First will throw an exception. FirstOrDefault will return null (or the type default if the IEnumerable is of a struct) if the list is empty, Depending on your use case, you should decide which is better for you.

Edit

The list in the question, is not List<T> but rather a ListBox as was clarified. You can take the Items property, use Cast to get an IEnumerable<T> and then use Fist. I am assuming the objects in the ListBox are string but you should change that to whatever type you are using:

listBox1.Items.Cast<string>().FirstOrDefault();

edited Feb 22 '18 at 18:53

answered Feb 22 '18 at 18:26

Titian Cernicova-Dragomir

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the program is still complaining even when i was adding system.Linq the error which I have is: ListBox does not contain a definition for First and no extension method first..... – Bogdan Dragos Feb 22 '18 at 18:31
1

worth pointing out will throw exception if no item in collection – Ehsan Sajjad Feb 22 '18 at 18:34
Agree with @EhsanSajjad - It would be better to call `FirstOrDefault` then check for `null`. However, question seems to be a duplicate of existing one – Aleks Andreev Feb 22 '18 at 18:37
still does not work, I was looking at the similar question and getting the code from there, still nothing, is still complaining – Bogdan Dragos Feb 22 '18 at 18:43
@BogdanDragos Your fist iteration of the question did not mention the `ListBox`, only a `List`. Are you using WinForms ? – Titian Cernicova-Dragomir Feb 22 '18 at 18:45
indeed, I am creating the program in windows forms c# – Bogdan Dragos Feb 22 '18 at 18:46
@BogdanDragos Edited the answer – Titian Cernicova-Dragomir Feb 22 '18 at 18:50
That's because you should be looking at the `Items` property: https://msdn.microsoft.com/en-us/library/system.windows.forms.listbox.items(v=vs.110).aspx – JuanR Feb 22 '18 at 18:50

score 0 · Answer 2 · answered Feb 22 '18 at 18:27

0

Use .First() or .FirstOrDefault():

using System.Linq; // don't forget to add this.

var firstItem = yourList.First();

answered Feb 22 '18 at 18:27

A-Sharabiani

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first element of the listBox c#

2 Answers2