List<T>.FindIndex for multiple results?
<p>let's say, we have a List with</p>

<pre><code>List&lt;int&gt; lst = new List&lt;int&gt;();
lst.Add(20);
lst.Add(10);
lst.Add(30);
lst.Add(10);
lst.Add(90);
</code></pre>

<p>If I need to get the index of the first element that is 20 I would use</p>

<pre><code>FindIndex()
</code></pre>

<p>But is there a method which can be used for multiple results?
Let's say I would like to have the index of elements having the number 10.</p>

<p>I know there is a method FindAll() but this gives me a new List insted of the indexes.</p>

<p>The best(?) method would be to get an array of indexes.</p>

<p>THanks in advance
John</p>
