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187 lines
8.5 KiB
HTML
187 lines
8.5 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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this GNU Manual. Buying copies from GNU Press supports the FSF in
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developing GNU and promoting software freedom." -->
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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>Additions to Ada (Debugging with GDB)</title>
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<meta name="description" content="Additions to Ada (Debugging with GDB)">
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<meta name="keywords" content="Additions to Ada (Debugging with GDB)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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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="Ada.html#Ada" rel="up" title="Ada">
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<link href="Overloading-support-for-Ada.html#Overloading-support-for-Ada" rel="next" title="Overloading support for Ada">
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<link href="Omissions-from-Ada.html#Omissions-from-Ada" rel="prev" title="Omissions from Ada">
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<style type="text/css">
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<!--
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a.summary-letter {text-decoration: none}
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blockquote.indentedblock {margin-right: 0em}
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blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
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blockquote.smallquotation {font-size: smaller}
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div.display {margin-left: 3.2em}
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div.example {margin-left: 3.2em}
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div.lisp {margin-left: 3.2em}
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div.smalldisplay {margin-left: 3.2em}
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div.smallexample {margin-left: 3.2em}
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div.smalllisp {margin-left: 3.2em}
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kbd {font-style: oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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pre.menu-preformatted {font-family: serif}
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pre.smalldisplay {font-family: inherit; font-size: smaller}
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pre.smalllisp {font-size: smaller}
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span.nolinebreak {white-space: nowrap}
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span.roman {font-family: initial; font-weight: normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Additions-to-Ada"></a>
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<div class="header">
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<p>
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Next: <a href="Overloading-support-for-Ada.html#Overloading-support-for-Ada" accesskey="n" rel="next">Overloading support for Ada</a>, Previous: <a href="Omissions-from-Ada.html#Omissions-from-Ada" accesskey="p" rel="prev">Omissions from Ada</a>, Up: <a href="Ada.html#Ada" accesskey="u" rel="up">Ada</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="Additions-to-Ada-1"></a>
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<h4 class="subsubsection">15.4.10.3 Additions to Ada</h4>
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<a name="index-Ada_002c-deviations-from"></a>
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<p>As it does for other languages, <small>GDB</small> makes certain generic
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extensions to Ada (see <a href="Expressions.html#Expressions">Expressions</a>):
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</p>
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<ul>
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<li> If the expression <var>E</var> is a variable residing in memory (typically
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a local variable or array element) and <var>N</var> is a positive integer,
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then <code><var>E</var>@<var>N</var></code> displays the values of <var>E</var> and the
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<var>N</var>-1 adjacent variables following it in memory as an array. In
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Ada, this operator is generally not necessary, since its prime use is
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in displaying parts of an array, and slicing will usually do this in
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Ada. However, there are occasional uses when debugging programs in
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which certain debugging information has been optimized away.
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</li><li> <code><var>B</var>::<var>var</var></code> means “the variable named <var>var</var> that
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appears in function or file <var>B</var>.” When <var>B</var> is a file name,
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you must typically surround it in single quotes.
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</li><li> The expression <code>{<var>type</var>} <var>addr</var></code> means “the variable of type
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<var>type</var> that appears at address <var>addr</var>.”
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</li><li> A name starting with ‘<samp>$</samp>’ is a convenience variable
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(see <a href="Convenience-Vars.html#Convenience-Vars">Convenience Vars</a>) or a machine register (see <a href="Registers.html#Registers">Registers</a>).
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</li></ul>
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<p>In addition, <small>GDB</small> provides a few other shortcuts and outright
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additions specific to Ada:
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</p>
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<ul>
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<li> The assignment statement is allowed as an expression, returning
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its right-hand operand as its value. Thus, you may enter
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<div class="smallexample">
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<pre class="smallexample">(gdb) set x := y + 3
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(gdb) print A(tmp := y + 1)
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</pre></div>
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</li><li> The semicolon is allowed as an “operator,” returning as its value
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the value of its right-hand operand.
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This allows, for example,
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complex conditional breaks:
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<div class="smallexample">
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<pre class="smallexample">(gdb) break f
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(gdb) condition 1 (report(i); k += 1; A(k) > 100)
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</pre></div>
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</li><li> Rather than use catenation and symbolic character names to introduce special
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characters into strings, one may instead use a special bracket notation,
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which is also used to print strings. A sequence of characters of the form
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‘<samp>["<var>XX</var>"]</samp>’ within a string or character literal denotes the
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(single) character whose numeric encoding is <var>XX</var> in hexadecimal. The
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sequence of characters ‘<samp>["""]</samp>’ also denotes a single quotation mark
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in strings. For example,
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<div class="smallexample">
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<pre class="smallexample"> "One line.["0a"]Next line.["0a"]"
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</pre></div>
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<p>contains an ASCII newline character (<code>Ada.Characters.Latin_1.LF</code>)
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after each period.
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</p>
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</li><li> The subtype used as a prefix for the attributes <tt>'Pos</tt>, <tt>'Min</tt>, and
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<tt>'Max</tt> is optional (and is ignored in any case). For example, it is valid
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to write
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<div class="smallexample">
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<pre class="smallexample">(gdb) print 'max(x, y)
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</pre></div>
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</li><li> When printing arrays, <small>GDB</small> uses positional notation when the
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array has a lower bound of 1, and uses a modified named notation otherwise.
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For example, a one-dimensional array of three integers with a lower bound
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of 3 might print as
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<div class="smallexample">
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<pre class="smallexample">(3 => 10, 17, 1)
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</pre></div>
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<p>That is, in contrast to valid Ada, only the first component has a <code>=></code>
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clause.
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</p>
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</li><li> You may abbreviate attributes in expressions with any unique,
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multi-character subsequence of
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their names (an exact match gets preference).
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For example, you may use <tt>a'len</tt>, <tt>a'gth</tt>, or <tt>a'lh</tt>
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in place of <tt>a'length</tt>.
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</li><li> <a name="index-quoting-Ada-internal-identifiers"></a>
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Since Ada is case-insensitive, the debugger normally maps identifiers you type
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to lower case. The GNAT compiler uses upper-case characters for
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some of its internal identifiers, which are normally of no interest to users.
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For the rare occasions when you actually have to look at them,
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enclose them in angle brackets to avoid the lower-case mapping.
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For example,
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<div class="smallexample">
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<pre class="smallexample">(gdb) print <JMPBUF_SAVE>[0]
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</pre></div>
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</li><li> Printing an object of class-wide type or dereferencing an
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access-to-class-wide value will display all the components of the object’s
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specific type (as indicated by its run-time tag). Likewise, component
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selection on such a value will operate on the specific type of the
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object.
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</li></ul>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Overloading-support-for-Ada.html#Overloading-support-for-Ada" accesskey="n" rel="next">Overloading support for Ada</a>, Previous: <a href="Omissions-from-Ada.html#Omissions-from-Ada" accesskey="p" rel="prev">Omissions from Ada</a>, Up: <a href="Ada.html#Ada" accesskey="u" rel="up">Ada</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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</body>
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</html>
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