Databases
StackOverflow2013
Postsdbo
POHow fast is operation on KeyCollection returned by Dictionary.Keys ? (.NET)
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow fast is operation on KeyCollection returned by Dictionary.Keys ? (.NET)
    primarykey
    data
    text
    <p><a href="http://msdn.microsoft.com/en-us/library/s4ys34ea.aspx" rel="nofollow"><code>IDictionary&lt;TK, TV&gt;</code></a> defines method <a href="http://msdn.microsoft.com/en-us/library/htszx2dy.aspx" rel="nofollow"><code>IDictionary.ContainsKey(in TK)</code></a> and property <a href="http://msdn.microsoft.com/en-us/library/1ebzfbyx.aspx" rel="nofollow"><code>IDictionary.Keys</code></a> (of type <code>ICollection</code>). I'm interested in (asymptotic) complexity of this method and property in <a href="http://msdn.microsoft.com/en-us/library/xfhwa508.aspx" rel="nofollow"><code>Dictionary</code></a> implementation of <a href="http://msdn.microsoft.com/en-us/library/s4ys34ea.aspx" rel="nofollow"><code>IDictionary&lt;TK, TV&gt;</code></a>.</p> <p>Consider definitions </p> <pre><code>IDictionary&lt;int, string&gt; dict = new Dictionary&lt;int, string&gt;(); int k = new Random().Next(); </code></pre> <p>and consider that we have added to the dictionary <code>dict</code> <code>n</code> unique <code>KeyValuePair</code>s.</p> <p>What is expected (asymptotic) complexity of a call <code>dict.ContainsKey(k)</code>? I hope it's in <code>O(1)</code> but I did not find it in <a href="http://msdn.microsoft.com/en-us/library/kw5aaea4.aspx" rel="nofollow">documentation of <code>Dictionary.ContainsKey</code></a>.</p> <p>What is expected (asymptotic) complexity of call <code>dict.Keys.Contains(k)</code>? I hope it's in <code>O(1)</code>but I did not find it in <a href="http://msdn.microsoft.com/en-us/library/yt2fy5zk.aspx" rel="nofollow">documentation of <code>Dictionary.Keys</code></a> nor in <a href="http://msdn.microsoft.com/en-us/library/3fcwy8h6.aspx" rel="nofollow">documentation of <code>Dictionary.KeyCollection</code></a>. If it is in <code>O(1)</code> I don't understand why type of <code>IDictionary.Keys</code> property is <code>ICollection</code> and not <code>ISet</code> (like in Java for example).</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USdrasto
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow fast is operation on KeyCollection returned by Dictionary.Keys ? (.NET)
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POHow fast is operation on KeyCollection returned by Dictionary.Keys ? (.NET)
      1. USdrasto
      1. VTFavorite
    1. CONote: `ISet<T>` is new with .NET 4, `ICollection<T>` and `IDictionary<T, K>` have been around since .NET 2.
      singulars
      1. POHow fast is operation on KeyCollection returned by Dictionary.Keys ? (.NET)
      1. USAnthony Pegram
    2. COAnthony Pegram: then I hope they will change the type of `IDictionary.Keys` to `ISet` in .NET 5.
      singulars
      1. POHow fast is operation on KeyCollection returned by Dictionary.Keys ? (.NET)
      1. USdrasto
    3. COthat would be a breaking change for many customers. They're not going to do that. With that said, remember, it's just an interface, it can be implemented by anything. Indeed, to implement `ISet<T>`, you *must* implement `ICollection<T>`. Therefore, the actual object returned could very well implement `ISet<T>`. The interface type returned says nothing of the implementation details, merely the contract that is ackhowledged as fulfilled.
      singulars
      1. POHow fast is operation on KeyCollection returned by Dictionary.Keys ? (.NET)
      1. USAnthony Pegram
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload