What happens to C# Dictionary lookup if the key does not exist?

Question

I tried checking for null but the compiler warns that this condition will never occur. What should I be looking for?

Answer 1

A helper class is handy:

public static class DictionaryHelper
{
    public static TVal Get(this Dictionary dictionary, TKey key, TVal defaultVal = default(TVal))
    {
        TVal val;
        if( dictionary.TryGetValue(key, out val) )
        {
            return val;
        }
        return defaultVal;
    }
}