C++ -- When recompilation is required
<p>You have a class that many libraries depend on. You need to modify the class for one application. Which of the following changes require recompiling all libraries before it is safe to build the application?</p>

<ul>
<li>add a constructor</li>
<li>add a data member</li>
<li>change destructor into virtual</li>
<li>add an argument with default value to an existing member function</li>
</ul>

<p>Thank you</p>
