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

You should check for Dictionary.ContainsKey(int key) before trying to pull out the value.

Dictionary myDictionary = new Dictionary();
myDictionary.Add(2,4);
myDictionary.Add(3,5);

int keyToFind = 7;
if(myDictionary.ContainsKey(keyToFind))
{
    myValueLookup = myDictionay[keyToFind];
    // do work...
}
else
{
    // the key doesn't exist.
}