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POC# listbox Collection syntax
 

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    <p>While learning C# pretty fast, I am stumbling on this Collection syntax problem.</p> <p>I added a number of objects of my own type MyItem to listbox lstData. Now I need to search in this listbox and thought of using the elegant LINQ notation like:</p> <pre><code>lstData.Items.Where(x =&gt; x.Text == SearchString) </code></pre> <p>but the Items of a listbox does not have a .Where(), although I did include the "using System.Linq;" namespace.</p> <p>So I tried:</p> <pre><code>foreach (MyItem item in (MyItem)lstData.Items) </code></pre> <p>but this gives the build error: Cannot convert type 'System.Windows.Forms.ListBox.ObjectCollection' to 'MySandbox.frmListboxDemo.MyItem'.</p> <p>I did manage to write something workable:</p> <pre><code> for (int i = 0; i &lt; lstData.Items.Count; i++) { MyItem item = (MyItem)lstData.Items[i]; if (item.Text == SearchString) { lstData.SetSelected(i, true); break; } } </code></pre> <p>and a similar version like:</p> <pre><code> var item_enum = lstData.Items.GetEnumerator(); while (item_enum.MoveNext()) { etc etc... } </code></pre> <p>which turned out to be 2 lines longer, and without figuring what could replace 'var'.</p> <p>I am not really sure I understand how to use Collections, ObjectCollections, Enumerators etc, but am eager to learn. Especially if a .Where() version is possible and/or better.</p> <hr> <p>Thanks for all your answers. I ended up with this solution:</p> <pre><code> var item_iter = lstData.Items.Cast&lt;MyItem&gt;() .Where(x =&gt; x.Text.Trim().ToLower() == txtItemName.Text); foreach (MyItem item in item_iter) { int i = lstData.Items.IndexOf(item); lstData.SetSelected(i, true); break; } </code></pre> <p>I don't know if this is really much better than the "fortran" way (see above), but it does teach me methods I can use in other C# queries.</p>
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    1. COuse `.OfType<T>` ...
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      1. USAndreas Niedermair
 

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