What is the scope of these variables?
<p>Please see the C++ code fragment below:</p>

<pre><code>#include .....

Class1 class1;
Class2 class2;
...

void Class3::foo() {
    ...
}
</code></pre>

<p>What are the variables: class1 and class2?  Are they global variables?  Static variables?  What actually are these?  In C++ OO programming, is it good practice to use these because any member function of any class in the file can access them?  </p>

<p>Sorry for the beginner's question.</p>

<p>Thanks.</p>
