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113 lines
5.1 KiB
HTML
113 lines
5.1 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Free Software" and "Free Software Needs
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Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: "You are free to copy and modify
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>M2 Constants (Debugging with GDB)</title>
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<meta name="description" content="M2 Constants (Debugging with GDB)">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Modula_002d2.html#Modula_002d2" rel="up" title="Modula-2">
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<link href="M2-Types.html#M2-Types" rel="next" title="M2 Types">
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<link href="Built_002dIn-Func_002fProc.html#Built_002dIn-Func_002fProc" rel="prev" title="Built-In Func/Proc">
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</head>
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<body lang="en">
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<a name="M2-Constants"></a>
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<div class="header">
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<p>
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Next: <a href="M2-Types.html#M2-Types" accesskey="n" rel="next">M2 Types</a>, Previous: <a href="Built_002dIn-Func_002fProc.html#Built_002dIn-Func_002fProc" accesskey="p" rel="prev">Built-In Func/Proc</a>, Up: <a href="Modula_002d2.html#Modula_002d2" accesskey="u" rel="up">Modula-2</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Constants-1"></a>
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<h4 class="subsubsection">15.4.9.3 Constants</h4>
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<p><small>GDB</small> allows you to express the constants of Modula-2 in the following
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ways:
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</p>
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<ul>
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<li> Integer constants are simply a sequence of digits. When used in an
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expression, a constant is interpreted to be type-compatible with the
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rest of the expression. Hexadecimal integers are specified by a
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trailing ‘<samp>H</samp>’, and octal integers by a trailing ‘<samp>B</samp>’.
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</li><li> Floating point constants appear as a sequence of digits, followed by a
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decimal point and another sequence of digits. An optional exponent can
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then be specified, in the form ‘<samp>E<span class="roman">[</span>+<span class="roman">|</span>-<span class="roman">]</span><var>nnn</var></samp>’, where
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‘<samp><span class="roman">[</span>+<span class="roman">|</span>-<span class="roman">]</span><var>nnn</var></samp>’ is the desired exponent. All of the
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digits of the floating point constant must be valid decimal (base 10)
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digits.
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</li><li> Character constants consist of a single character enclosed by a pair of
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like quotes, either single (<code>'</code>) or double (<code>"</code>). They may
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also be expressed by their ordinal value (their <small>ASCII</small> value, usually)
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followed by a ‘<samp>C</samp>’.
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</li><li> String constants consist of a sequence of characters enclosed by a
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pair of like quotes, either single (<code>'</code>) or double (<code>"</code>).
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Escape sequences in the style of C are also allowed. See <a href="C-Constants.html#C-Constants">C and C<tt>++</tt> Constants</a>, for a brief explanation of escape
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sequences.
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</li><li> Enumerated constants consist of an enumerated identifier.
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</li><li> Boolean constants consist of the identifiers <code>TRUE</code> and
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<code>FALSE</code>.
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</li><li> Pointer constants consist of integral values only.
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</li><li> Set constants are not yet supported.
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</li></ul>
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</body>
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</html>
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