how is #if / #endif different than if?
<p>i am following this tutorial:</p>

<pre><code>        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            int i = 1;
            while (true)
            {
#if TEST
            if (i % 2 == 0)
                continue;
#endif
                i++;
                Console.WriteLine("The value of i is {0}", i);
                if (i &gt; 9)
                    break;
            }
            Console.WriteLine("The value of i is {0}", i);

            Application.Run(new Form1());
        }
</code></pre>

<p>what is the purpose of using <code>#if TEST</code> instead of just <code>if(TEST)</code> ??</p>
