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c#dictionarytrygetvalue

Should I always use Dictionary.TryGetValue even if I all want to do is add/replace values?

I've been using TryGetValue to add/replace data in my dictionaries. Just to make the distinction between adding new vs. replacing old, I use both [] and .Add(). This leads to code like this, if I am not actually doing anything with the retrieved value:

private Dictionary<Foo, Bar> dictionary = new Dictionary<Foo, Bar>();

public void Update(Foo foo)
{
    Bar bar;
    if (dictionary.TryGetValue(foo, out bar)
    {
        dictionary [foo] = bar;
    }
    else
    {
        dictionary .Add(foo, bar);
    }
}

If I am not actually doing anything with the retrieved value, is there a reason why I shouldn't replace the above code with this?:

public void Update(Foo foo)
{
    dictionary[foo] = bar;
}

Thank you in advance.

Solution

  • You should use the simpler code.
    It will be faster in all cases. (one hash lookup vs. two)

    More importantly, it's simpler.