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POHow to perform a binary search on IList<T>?
 

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  1. POHow to perform a binary search on IList<T>?
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    <p>Simple question - given an <code>IList&lt;T&gt;</code> how do you perform a binary search without writing the method yourself and without copying the data to a type with build-in binary search support. My current status is the following.</p> <ul> <li><code>List&lt;T&gt;.BinarySearch()</code> is not a member of <code>IList&lt;T&gt;</code></li> <li>There is no equivalent of the <a href="http://msdn.microsoft.com/en-us/library/system.collections.arraylist.adapter.aspx" rel="noreferrer"><code>ArrayList.Adapter()</code></a> method for <code>List&lt;T&gt;</code></li> <li><code>IList&lt;T&gt;</code> does not inherit from <code>IList</code>, hence using <code>ArrayList.Adapter()</code> is not possible</li> </ul> <p>I tend to believe that is not possible with build-in methods, but I cannot believe that such a basic method is missing from the BCL/FCL.</p> <p>If it is not possible, who can give the shortest, fastest, smartest, or most beatiful binary search implementation for <code>IList&lt;T&gt;</code>?</p> <p><strong>UPDATE</strong></p> <p>We all know that a list must be sorted before using binary search, hence you can assume that it is. But I assume (but did not verify) it is the same problem with sort - how do you sort <code>IList&lt;T&gt;</code>?</p> <p><strong>CONCLUSION</strong></p> <p>There seems to be no build-in binary search for <code>IList&lt;T&gt;</code>. One can use <code>First()</code> and <code>OrderBy()</code> LINQ methods to search and sort, but it will likly have a performance hit. Implementing it yourself (as an extension method) seems the best you can do.</p>
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    1. USDaniel Brückner
    1. USDaniel Brückner
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    1. COYou can't perform a binary search on any old data - it has to have been appropriately sorted and without duplicates first
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      1. POHow to perform a binary search on IList<T>?
      1. USJeff Yates
    2. COYou can assume that the list is sorted.
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      1. USDaniel Brückner
    3. CODo you know the underlying type of the object? List<T> does provide the Sort and BinarySearch methods.
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      1. POHow to perform a binary search on IList<T>?
      1. USPeter Ruderman
 

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