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POWhy can't I cast a dictionary of one value type to dictionary of another value type when the value types can be cast from one another?
 

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  1. POWhy can't I cast a dictionary of one value type to dictionary of another value type when the value types can be cast from one another?
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    <blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="https://stackoverflow.com/questions/6557/in-c-why-cant-a-liststring-object-be-stored-in-a-listobject-variable">In C#, why can&#39;t a List&lt;string&gt; object be stored in a List&lt;object&gt; variable</a> </p> </blockquote> <p>Why doesn't the below work?</p> <pre><code>List&lt;string&gt; castMe = new List&lt;string&gt;(); IEnumerable&lt;string&gt; getFromCast = (IEnumerable&lt;string&gt;)castMe; // allowed. Dictionary&lt;int, List&lt;string&gt;&gt; castMeDict = new Dictionary&lt;int, List&lt;string&gt;&gt;(); Dictionary&lt;int, IEnumerable&lt;string&gt;&gt; getFromDict = (Dictionary&lt;int, IEnumerable&lt;string&gt;&gt;)castMeDict; // Not allowed </code></pre> <p>Is this a flaw in the <code>Dictionary</code> casting mechanism, or in my thinking that this should be allowed?</p> <p>Thanks.</p>
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    1. COSee: [Understanding Covariant and Contravariant interfaces in C#](http://stackoverflow.com/questions/2719954/understanding-covariant-and-contravariant-interfaces-in-c-sharp)
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    2. COThanks everybody. Sorry, I did check for duplicates but it's a bit difficult to first generalize, then search for all specific instances that may be duplicates, without first knowing the answer.
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