EqualsArray.qhelp

<!DOCTYPE qhelp PUBLIC
  "-//Semmle//qhelp//EN"
  "qhelp.dtd">
<qhelp>
<overview>
<p>There are some circumstances where you want to compare two arrays or collections using reference equality, but 
often you will want a deep comparison instead (that is, one that compares two collections on an 
element-by-element basis).</p>

</overview>
<recommendation>
<p>If you intended to make a deep comparison then the solution depends on whether or not you are 
using C# 3.5 or later. From C# 3.5 onward LINQ is available and you can replace the call to <code>
Equals</code> with a call to the LINQ extension method <code>SequenceEqual</code>. If this is not 
possible then you can implement a helper function to compare arrays, which can then be used 
throughout your code.</p>

</recommendation>
<example>
<p>This example outputs "False" because calling <code>Equals</code> on an array only does a 
reference comparison.</p>
<sample src="EqualsArray.cs" />

<p>The following example outputs "True" twice and uses two different methods of performing a deep 
comparison of the array.</p>
<sample src="EqualsArrayFix.cs" />

</example>
<references>

  <li>MSDN: <a href="http://msdn.microsoft.com/en-us/library/system.linq.enumerable.sequenceequal.aspx">Enumerable.SequenceEqual Method</a>.</li>


</references>
</qhelp>