title: What is the difference between NUL and NULL?
body: <p><code>NULL</code> is a macro defined in <code>&lt;stddef.h&gt;</code> for the <code>null pointer</code>; it can be defined as <code>((void*)0)</code>. <code>NULL</code> is the name of the first character in the <code>ASCII</code> character set. What is the difference between them?</p>