76 lines
3.2 KiB
HTML
76 lines
3.2 KiB
HTML
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>Deviations - Debugging with GDB</title>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html">
|
||
|
|
<meta name="description" content="Debugging with GDB">
|
||
|
|
<meta name="generator" content="makeinfo 4.13">
|
||
|
|
<link title="Top" rel="start" href="index.html#Top">
|
||
|
|
<link rel="up" href="Modula_002d2.html#Modula_002d2" title="Modula-2">
|
||
|
|
<link rel="prev" href="M2-Defaults.html#M2-Defaults" title="M2 Defaults">
|
||
|
|
<link rel="next" href="M2-Checks.html#M2-Checks" title="M2 Checks">
|
||
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
||
|
|
<!--
|
||
|
|
Copyright (C) 1988-2019 Free Software Foundation, Inc.
|
||
|
|
|
||
|
|
Permission is granted to copy, distribute and/or modify this document
|
||
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
||
|
|
any later version published by the Free Software Foundation; with the
|
||
|
|
Invariant Sections being ``Free Software'' and ``Free Software Needs
|
||
|
|
Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
|
||
|
|
and with the Back-Cover Texts as in (a) below.
|
||
|
|
|
||
|
|
(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
|
||
|
|
this GNU Manual. Buying copies from GNU Press supports the FSF in
|
||
|
|
developing GNU and promoting software freedom.''
|
||
|
|
-->
|
||
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
||
|
|
<style type="text/css"><!--
|
||
|
|
pre.display { font-family:inherit }
|
||
|
|
pre.format { font-family:inherit }
|
||
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallexample { font-size:smaller }
|
||
|
|
pre.smalllisp { font-size:smaller }
|
||
|
|
span.sc { font-variant:small-caps }
|
||
|
|
span.roman { font-family:serif; font-weight:normal; }
|
||
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
||
|
|
--></style>
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<div class="node">
|
||
|
|
<a name="Deviations"></a>
|
||
|
|
<p>
|
||
|
|
Next: <a rel="next" accesskey="n" href="M2-Checks.html#M2-Checks">M2 Checks</a>,
|
||
|
|
Previous: <a rel="previous" accesskey="p" href="M2-Defaults.html#M2-Defaults">M2 Defaults</a>,
|
||
|
|
Up: <a rel="up" accesskey="u" href="Modula_002d2.html#Modula_002d2">Modula-2</a>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<h5 class="subsubsection">15.4.9.6 Deviations from Standard Modula-2</h5>
|
||
|
|
|
||
|
|
<p><a name="index-Modula_002d2_002c-deviations-from-1049"></a>
|
||
|
|
A few changes have been made to make Modula-2 programs easier to debug.
|
||
|
|
This is done primarily via loosening its type strictness:
|
||
|
|
|
||
|
|
<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>C escape sequences can be used in strings and characters to represent
|
||
|
|
non-printable characters. <span class="sc">gdb</span> prints out strings with these
|
||
|
|
escape sequences embedded. Single non-printable characters are
|
||
|
|
printed using the ‘<samp><span class="samp">CHR(</span><var>nnn</var><span class="samp">)</span></samp>’ format.
|
||
|
|
|
||
|
|
<li>The assignment operator (<code>:=</code>) returns the value of its right-hand
|
||
|
|
argument.
|
||
|
|
|
||
|
|
<li>All built-in procedures both modify <em>and</em> return their argument.
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
</body></html>
|
||
|
|
|