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<a name="Deviations-from-Standard-Modula_002d2"></a>
<h4 class="subsubsection">15.4.9.6 Deviations from Standard Modula-2</h4>
<a name="index-Modula_002d2_002c-deviations-from"></a>

<p>A few changes have been made to make Modula-2 programs easier to debug.
This is done primarily via loosening its type strictness:
</p>
<ul>
<li> Unlike in standard Modula-2, pointer constants can be formed by
integers.  This allows you to modify pointer variables during
debugging.  (In standard Modula-2, the actual address contained in a
pointer variable is hidden from you; it can only be modified
through direct assignment to another pointer variable or expression that
returned a pointer.)

</li><li> C escape sequences can be used in strings and characters to represent
non-printable characters.  <small>GDB</small> prints out strings with these
escape sequences embedded.  Single non-printable characters are
printed using the &lsquo;<samp>CHR(<var>nnn</var>)</samp>&rsquo; format.

</li><li> The assignment operator (<code>:=</code>) returns the value of its right-hand
argument.

</li><li> All built-in procedures both modify <em>and</em> return their argument.
</li></ul>


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