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copied!<p>It is perhaps easier to understand if you think about the underlying representation (even though this really is an implementation detail). Here is a collection of strings:</p> <pre><code>IEnumerable<string> strings = new[] { "A", "B", "C" }; </code></pre> <p>You can think of the <code>strings</code> as having the following representation:</p> <pre> [0] : string reference -> "A" [1] : string reference -> "B" [2] : string reference -> "C" </pre> <p>It is a collection of three elements, each being a reference to a string. You can cast this to a collection of objects:</p> <pre><code>IEnumerable<object> objects = (IEnumerable<object>) strings; </code></pre> <p>Basically it is the same representation except now the references are object references:</p> <pre> [0] : object reference -> "A" [1] : object reference -> "B" [2] : object reference -> "C" </pre> <p>The representation is the same. The references are just treated differently; you can no longer access the <code>string.Length</code> property but you can still call <code>object.GetHashCode()</code>. Compare this to a collection of ints:</p> <pre><code>IEnumerable<int> ints = new[] { 1, 2, 3 }; </code></pre> <pre> [0] : int = 1 [1] : int = 2 [2] : int = 3 </pre> <p>To convert this to an <code>IEnumerable<object></code> the data has to be converted by boxing the ints:</p> <pre> [0] : object reference -> 1 [1] : object reference -> 2 [2] : object reference -> 3 </pre> <p>This conversion requires more than a cast.</p>

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