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    <p>Simply speaking, the default comparator compares object instances.</p> <ul> <li><p>In your first example, both <code>_emp1</code> and <code>_emp2</code> are pointing to the same instance of <code>Employee</code> and therefore <code>Equals</code> returns true.</p></li> <li><p>In your second example, you create two <code>Employee</code> objects, <code>_emp1</code> and <code>_emp2</code> being two distinctly different objects. Therefore, <code>Equals</code> returns false.</p></li> </ul> <hr> <p>Note that copy constructors are <em>not implicitly called</em> for reference types. Were you to do:</p> <pre><code>Employee _emp1 = new Employee(); Employee _emp2 = new Employee(_emp1); //or _emp1.Clone() if that is implemented </code></pre> <p>then <code>Equals</code> using a the default comparator will return false since they are two unique objects.</p> <p>Also note that this behavior is <em>not the same</em> for value types.</p> <hr> <p>Furthermore, if you (as you should) override the default behavior of <code>Equals</code> and <code>CompareTo</code>, all the above becomes moot. A standard technique might be (assuming a little bit):</p> <pre><code>public bool Equals(object rhs) { var rhsEmployee = rhs as Employee; if(rhsEmployee == null) return false; return this.Equals(rhsEmployee); } public bool Equals(Employee rhs) { return this.EmployeeId == rhs.EmployeeId; } </code></pre> <hr> <p>Further reading:</p> <ul> <li><a href="http://msdn.microsoft.com/en-us/library/bsc2ak47.aspx" rel="nofollow"><code>Object.Equals</code></a></li> <li><a href="http://msdn.microsoft.com/en-us/library/system.object.referenceequals.aspx" rel="nofollow"><code>Object.ReferenceEquals</code></a></li> <li><a href="http://msdn.microsoft.com/en-us/library/t63sy5hs%28v=vs.80%29.aspx" rel="nofollow">Value Types and Reference Types</a></li> </ul>
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    1. COIn your first Bullet you mean to say: _emp1 and _emp2 both point to the same Memory Location. and in Second _emp1 and _emp2 point to two different memory location. Well has this anything to do with Stacks, Heap??
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    2. CO@LetsKickSomeAssin.net Semantically it is the same thing, yes. However, in the Managed world, we tend to avoid talking directly about memory as we usually do not have direct control over it. But yes, under the hood it is checking [`Object.ReferenceEquals`](http://msdn.microsoft.com/en-us/library/system.object.referenceequals.aspx) which compares the two pointer values.
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    3. COThis won't compile, as the compiler refuses to convert `null` to `bool`. If the other instance is no `Employee`, `Equals` should return `false`.
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