Performance for myCollection.Add() vs. myCollection["key"]
When dealing 开发者_Go百科with a collection of key/value pairs is there any difference between using its Add() method and directly assigning it?
For example, a HtmlGenericControl will have an Attributes Collection:
var anchor = new HtmlGenericControl("a");
// These both work:
anchor.Attributes.Add("class", "xyz");
anchor.Attributes["class"] = "xyz";
Is it purely a matter of preference, or is there a reason for doing one or the other?
They are equivalent for your use, in this case, running this:
anchor.Attributes["class"] = "xyz";
Actually calls this internally:
anchor.Attributes.Add("class", "xyz");
In AttributeCollection
the this[string key]
setter looks like this:
public string this[string key]
{
get { }
set { this.Add(key, value); }
}
So to answer the question, in the case of AttributeCollection
, it's just a matter of preference. Keep in mind, this isn't true for other collection types, for example Dictionary<T, TValue>
. In this case ["class"] = "xyz"
would update or set the value, where .Add("class", "xyz")
(if it already had a "class"
entry) would throw a duplicate entry error.
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