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copied!<p>Objects aren't passed by reference. Objects aren't passed at all.</p> <p>By default, the value of the argument is passed by value - whether that value is a value type value or a reference. If an object is modified via that reference, then that change will be visible to the calling code as well.</p> <p>In the code you showed originally, there was no reason to use <code>ref</code>. The <code>ref</code> keyword is used when you want a method that changes the value of a <em>parameter</em> (e.g. to make it refer to a different object entirely) and have that change visible to the caller.</p> <p>Now, in the code you've shown (originally) you've only got:</p> <pre><code>private int BindMyObject(object reader, MyObject obj) { //make changes to obj in here } </code></pre> <p>Do you mean code like this:</p> <pre><code>private int BindMyObject(object reader, MyObject obj) { obj = new MyObject(); } </code></pre> <p>or code like this:</p> <pre><code>private int BindMyObject(object reader, MyObject obj) { obj.SomeProperty = differentValue; } </code></pre> <p>? If it's the latter, then you don't need <code>ref</code>. If it's the former, then you <em>do</em> need <code>ref</code> because you're changing the parameter itself, not making changes to the object that the value refers to. In fact, if you're <em>just</em> setting the value of <code>obj</code> without ever reading it, you should use <code>out</code> instead of <code>ref</code>.</p> <p>If you can show a short but <em>complete</em> program which demonstrates your problem, it'll be a lot easier to explain what's going on.</p> <p>It's hard to do this topic justice in just a few paragraphs - so I've got an <a href="http://pobox.com/~skeet/csharp/parameters.html" rel="noreferrer">entire article about it</a>, which will hopefully make things more obvious. </p>

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