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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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diff --git a/share/doc/gdb/Print-Settings.html b/share/doc/gdb/Print-Settings.html new file mode 100644 index 0000000..cdf17d6 --- /dev/null +++ b/share/doc/gdb/Print-Settings.html @@ -0,0 +1,886 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 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." --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Debugging with GDB: Print Settings</title> + +<meta name="description" content="Debugging with GDB: Print Settings"> +<meta name="keywords" content="Debugging with GDB: Print Settings"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Data.html#Data" rel="up" title="Data"> +<link href="Pretty-Printing.html#Pretty-Printing" rel="next" title="Pretty Printing"> +<link href="Auto-Display.html#Auto-Display" rel="previous" title="Auto Display"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Print-Settings"></a> +<div class="header"> +<p> +Next: <a href="Pretty-Printing.html#Pretty-Printing" accesskey="n" rel="next">Pretty Printing</a>, Previous: <a href="Auto-Display.html#Auto-Display" accesskey="p" rel="previous">Auto Display</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</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> +</div> +<hr> +<a name="Print-Settings-1"></a> +<h3 class="section">10.9 Print Settings</h3> + +<a name="index-format-options"></a> +<a name="index-print-settings"></a> +<p><small>GDB</small> provides the following ways to control how arrays, structures, +and symbols are printed. +</p> +<p>These settings are useful for debugging programs in any language: +</p> +<dl compact="compact"> +<dd><a name="index-set-print"></a> +<a name="set-print-address"></a></dd> +<dt><code>set print address</code></dt> +<dt><code>set print address on</code></dt> +<dd><a name="index-print_002fdon_0027t-print-memory-addresses"></a> +<p><small>GDB</small> prints memory addresses showing the location of stack +traces, structure values, pointer values, breakpoints, and so forth, +even when it also displays the contents of those addresses. The default +is <code>on</code>. For example, this is what a stack frame display looks like with +<code>set print address on</code>: +</p> +<div class="smallexample"> +<pre class="smallexample">(gdb) f +#0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>") + at input.c:530 +530 if (lquote != def_lquote) +</pre></div> + +</dd> +<dt><code>set print address off</code></dt> +<dd><p>Do not print addresses when displaying their contents. For example, +this is the same stack frame displayed with <code>set print address off</code>: +</p> +<div class="smallexample"> +<pre class="smallexample">(gdb) set print addr off +(gdb) f +#0 set_quotes (lq="<<", rq=">>") at input.c:530 +530 if (lquote != def_lquote) +</pre></div> + +<p>You can use ‘<samp>set print address off</samp>’ to eliminate all machine +dependent displays from the <small>GDB</small> interface. For example, with +<code>print address off</code>, you should get the same text for backtraces on +all machines—whether or not they involve pointer arguments. +</p> +<a name="index-show-print"></a> +</dd> +<dt><code>show print address</code></dt> +<dd><p>Show whether or not addresses are to be printed. +</p></dd> +</dl> + +<p>When <small>GDB</small> prints a symbolic address, it normally prints the +closest earlier symbol plus an offset. If that symbol does not uniquely +identify the address (for example, it is a name whose scope is a single +source file), you may need to clarify. One way to do this is with +<code>info line</code>, for example ‘<samp>info line *0x4537</samp>’. Alternately, +you can set <small>GDB</small> to print the source file and line number when +it prints a symbolic address: +</p> +<dl compact="compact"> +<dt><code>set print symbol-filename on</code></dt> +<dd><a name="index-source-file-and-line-of-a-symbol"></a> +<a name="index-symbol_002c-source-file-and-line"></a> +<p>Tell <small>GDB</small> to print the source file name and line number of a +symbol in the symbolic form of an address. +</p> +</dd> +<dt><code>set print symbol-filename off</code></dt> +<dd><p>Do not print source file name and line number of a symbol. This is the +default. +</p> +</dd> +<dt><code>show print symbol-filename</code></dt> +<dd><p>Show whether or not <small>GDB</small> will print the source file name and +line number of a symbol in the symbolic form of an address. +</p></dd> +</dl> + +<p>Another situation where it is helpful to show symbol filenames and line +numbers is when disassembling code; <small>GDB</small> shows you the line +number and source file that corresponds to each instruction. +</p> +<p>Also, you may wish to see the symbolic form only if the address being +printed is reasonably close to the closest earlier symbol: +</p> +<dl compact="compact"> +<dt><code>set print max-symbolic-offset <var>max-offset</var></code></dt> +<dt><code>set print max-symbolic-offset unlimited</code></dt> +<dd><a name="index-maximum-value-for-offset-of-closest-symbol"></a> +<p>Tell <small>GDB</small> to only display the symbolic form of an address if the +offset between the closest earlier symbol and the address is less than +<var>max-offset</var>. The default is <code>unlimited</code>, which tells <small>GDB</small> +to always print the symbolic form of an address if any symbol precedes +it. Zero is equivalent to <code>unlimited</code>. +</p> +</dd> +<dt><code>show print max-symbolic-offset</code></dt> +<dd><p>Ask how large the maximum offset is that <small>GDB</small> prints in a +symbolic address. +</p></dd> +</dl> + +<a name="index-wild-pointer_002c-interpreting"></a> +<a name="index-pointer_002c-finding-referent"></a> +<p>If you have a pointer and you are not sure where it points, try +‘<samp>set print symbol-filename on</samp>’. Then you can determine the name +and source file location of the variable where it points, using +‘<samp>p/a <var>pointer</var></samp>’. This interprets the address in symbolic form. +For example, here <small>GDB</small> shows that a variable <code>ptt</code> points +at another variable <code>t</code>, defined in <samp>hi2.c</samp>: +</p> +<div class="smallexample"> +<pre class="smallexample">(gdb) set print symbol-filename on +(gdb) p/a ptt +$4 = 0xe008 <t in hi2.c> +</pre></div> + +<blockquote> +<p><em>Warning:</em> For pointers that point to a local variable, ‘<samp>p/a</samp>’ +does not show the symbol name and filename of the referent, even with +the appropriate <code>set print</code> options turned on. +</p></blockquote> + +<p>You can also enable ‘<samp>/a</samp>’-like formatting all the time using +‘<samp>set print symbol on</samp>’: +</p> +<a name="set-print-symbol"></a><dl compact="compact"> +<dt><code>set print symbol on</code></dt> +<dd><p>Tell <small>GDB</small> to print the symbol corresponding to an address, if +one exists. +</p> +</dd> +<dt><code>set print symbol off</code></dt> +<dd><p>Tell <small>GDB</small> not to print the symbol corresponding to an +address. In this mode, <small>GDB</small> will still print the symbol +corresponding to pointers to functions. This is the default. +</p> +</dd> +<dt><code>show print symbol</code></dt> +<dd><p>Show whether <small>GDB</small> will display the symbol corresponding to an +address. +</p></dd> +</dl> + +<p>Other settings control how different kinds of objects are printed: +</p> +<dl compact="compact"> +<dd><a name="set-print-array"></a></dd> +<dt><code>set print array</code></dt> +<dt><code>set print array on</code></dt> +<dd><a name="index-pretty-print-arrays"></a> +<p>Pretty print arrays. This format is more convenient to read, +but uses more space. The default is off. +</p> +</dd> +<dt><code>set print array off</code></dt> +<dd><p>Return to compressed format for arrays. +</p> +</dd> +<dt><code>show print array</code></dt> +<dd><p>Show whether compressed or pretty format is selected for displaying +arrays. +</p> +<a name="index-print-array-indexes"></a> +<a name="set-print-array_002dindexes"></a></dd> +<dt><code>set print array-indexes</code></dt> +<dt><code>set print array-indexes on</code></dt> +<dd><p>Print the index of each element when displaying arrays. May be more +convenient to locate a given element in the array or quickly find the +index of a given element in that printed array. The default is off. +</p> +</dd> +<dt><code>set print array-indexes off</code></dt> +<dd><p>Stop printing element indexes when displaying arrays. +</p> +</dd> +<dt><code>show print array-indexes</code></dt> +<dd><p>Show whether the index of each element is printed when displaying +arrays. +</p> +<a name="set-print-nibbles"></a></dd> +<dt><code>set print nibbles</code></dt> +<dt><code>set print nibbles on</code></dt> +<dd><a name="index-print-binary-values-in-groups-of-four-bits"></a> +<p>Print binary values in groups of four bits, known as <em>nibbles</em>, +when using the print command of <small>GDB</small> with the option ‘<samp>/t</samp>’. +For example, this is what it looks like with <code>set print nibbles on</code>: +</p> +<div class="smallexample"> +<pre class="smallexample">(gdb) print val_flags +$1 = 1230 +(gdb) print/t val_flags +$2 = 0100 1100 1110 +</pre></div> + +</dd> +<dt><code>set print nibbles off</code></dt> +<dd><p>Don’t printing binary values in groups. This is the default. +</p> +</dd> +<dt><code>show print nibbles</code></dt> +<dd><p>Show whether to print binary values in groups of four bits. +</p> +<a name="set-print-elements"></a></dd> +<dt><code>set print elements <var>number-of-elements</var></code></dt> +<dt><code>set print elements unlimited</code></dt> +<dd><a name="index-number-of-array-elements-to-print"></a> +<a name="index-limit-on-number-of-printed-array-elements"></a> +<p>Set a limit on how many elements of an array <small>GDB</small> will print. +If <small>GDB</small> is printing a large array, it stops printing after it has +printed the number of elements set by the <code>set print elements</code> command. +This limit also applies to the display of strings. +When <small>GDB</small> starts, this limit is set to 200. +Setting <var>number-of-elements</var> to <code>unlimited</code> or zero means +that the number of elements to print is unlimited. +</p> +</dd> +<dt><code>show print elements</code></dt> +<dd><p>Display the number of elements of a large array that <small>GDB</small> will print. +</p> +<a name="set-print-frame_002darguments"></a></dd> +<dt><code>set print frame-arguments <var>value</var></code></dt> +<dd><a name="index-set-print-frame_002darguments"></a> +<a name="index-printing-frame-argument-values"></a> +<a name="index-print-all-frame-argument-values"></a> +<a name="index-print-frame-argument-values-for-scalars-only"></a> +<a name="index-do-not-print-frame-arguments"></a> +<p>This command allows to control how the values of arguments are printed +when the debugger prints a frame (see <a href="Frames.html#Frames">Frames</a>). The possible +values are: +</p> +<dl compact="compact"> +<dt><code>all</code></dt> +<dd><p>The values of all arguments are printed. +</p> +</dd> +<dt><code>scalars</code></dt> +<dd><p>Print the value of an argument only if it is a scalar. The value of more +complex arguments such as arrays, structures, unions, etc, is replaced +by <code>…</code>. This is the default. Here is an example where +only scalar arguments are shown: +</p> +<div class="smallexample"> +<pre class="smallexample">#1 0x08048361 in call_me (i=3, s=…, ss=0xbf8d508c, u=…, e=green) + at frame-args.c:23 +</pre></div> + +</dd> +<dt><code>none</code></dt> +<dd><p>None of the argument values are printed. Instead, the value of each argument +is replaced by <code>…</code>. In this case, the example above now becomes: +</p> +<div class="smallexample"> +<pre class="smallexample">#1 0x08048361 in call_me (i=…, s=…, ss=…, u=…, e=…) + at frame-args.c:23 +</pre></div> + +</dd> +<dt><code>presence</code></dt> +<dd><p>Only the presence of arguments is indicated by <code>…</code>. +The <code>…</code> are not printed for function without any arguments. +None of the argument names and values are printed. +In this case, the example above now becomes: +</p> +<div class="smallexample"> +<pre class="smallexample">#1 0x08048361 in call_me (…) at frame-args.c:23 +</pre></div> + +</dd> +</dl> + +<p>By default, only scalar arguments are printed. This command can be used +to configure the debugger to print the value of all arguments, regardless +of their type. However, it is often advantageous to not print the value +of more complex parameters. For instance, it reduces the amount of +information printed in each frame, making the backtrace more readable. +Also, it improves performance when displaying Ada frames, because +the computation of large arguments can sometimes be CPU-intensive, +especially in large applications. Setting <code>print frame-arguments</code> +to <code>scalars</code> (the default), <code>none</code> or <code>presence</code> avoids +this computation, thus speeding up the display of each Ada frame. +</p> +</dd> +<dt><code>show print frame-arguments</code></dt> +<dd><p>Show how the value of arguments should be displayed when printing a frame. +</p> +<a name="set-print-raw_002dframe_002darguments"></a></dd> +<dt><code>set print raw-frame-arguments on</code></dt> +<dd><p>Print frame arguments in raw, non pretty-printed, form. +</p> +</dd> +<dt><code>set print raw-frame-arguments off</code></dt> +<dd><p>Print frame arguments in pretty-printed form, if there is a pretty-printer +for the value (see <a href="Pretty-Printing.html#Pretty-Printing">Pretty Printing</a>), +otherwise print the value in raw form. +This is the default. +</p> +</dd> +<dt><code>show print raw-frame-arguments</code></dt> +<dd><p>Show whether to print frame arguments in raw form. +</p> +<a name="set-print-entry_002dvalues"></a></dd> +<dt><code>set print entry-values <var>value</var></code></dt> +<dd><a name="index-set-print-entry_002dvalues"></a> +<p>Set printing of frame argument values at function entry. In some cases +<small>GDB</small> can determine the value of function argument which was passed by +the function caller, even if the value was modified inside the called function +and therefore is different. With optimized code, the current value could be +unavailable, but the entry value may still be known. +</p> +<p>The default value is <code>default</code> (see below for its description). Older +<small>GDB</small> behaved as with the setting <code>no</code>. Compilers not supporting +this feature will behave in the <code>default</code> setting the same way as with the +<code>no</code> setting. +</p> +<p>This functionality is currently supported only by DWARF 2 debugging format and +the compiler has to produce ‘<samp>DW_TAG_call_site</samp>’ tags. With +<small>GCC</small>, you need to specify <samp>-O -g</samp> during compilation, to get +this information. +</p> +<p>The <var>value</var> parameter can be one of the following: +</p> +<dl compact="compact"> +<dt><code>no</code></dt> +<dd><p>Print only actual parameter values, never print values from function entry +point. +</p><div class="smallexample"> +<pre class="smallexample">#0 equal (val=5) +#0 different (val=6) +#0 lost (val=<optimized out>) +#0 born (val=10) +#0 invalid (val=<optimized out>) +</pre></div> + +</dd> +<dt><code>only</code></dt> +<dd><p>Print only parameter values from function entry point. The actual parameter +values are never printed. +</p><div class="smallexample"> +<pre class="smallexample">#0 equal (val@entry=5) +#0 different (val@entry=5) +#0 lost (val@entry=5) +#0 born (val@entry=<optimized out>) +#0 invalid (val@entry=<optimized out>) +</pre></div> + +</dd> +<dt><code>preferred</code></dt> +<dd><p>Print only parameter values from function entry point. If value from function +entry point is not known while the actual value is known, print the actual +value for such parameter. +</p><div class="smallexample"> +<pre class="smallexample">#0 equal (val@entry=5) +#0 different (val@entry=5) +#0 lost (val@entry=5) +#0 born (val=10) +#0 invalid (val@entry=<optimized out>) +</pre></div> + +</dd> +<dt><code>if-needed</code></dt> +<dd><p>Print actual parameter values. If actual parameter value is not known while +value from function entry point is known, print the entry point value for such +parameter. +</p><div class="smallexample"> +<pre class="smallexample">#0 equal (val=5) +#0 different (val=6) +#0 lost (val@entry=5) +#0 born (val=10) +#0 invalid (val=<optimized out>) +</pre></div> + +</dd> +<dt><code>both</code></dt> +<dd><p>Always print both the actual parameter value and its value from function entry +point, even if values of one or both are not available due to compiler +optimizations. +</p><div class="smallexample"> +<pre class="smallexample">#0 equal (val=5, val@entry=5) +#0 different (val=6, val@entry=5) +#0 lost (val=<optimized out>, val@entry=5) +#0 born (val=10, val@entry=<optimized out>) +#0 invalid (val=<optimized out>, val@entry=<optimized out>) +</pre></div> + +</dd> +<dt><code>compact</code></dt> +<dd><p>Print the actual parameter value if it is known and also its value from +function entry point if it is known. If neither is known, print for the actual +value <code><optimized out></code>. If not in MI mode (see <a href="GDB_002fMI.html#GDB_002fMI">GDB/MI</a>) and if both +values are known and identical, print the shortened +<code>param=param@entry=VALUE</code> notation. +</p><div class="smallexample"> +<pre class="smallexample">#0 equal (val=val@entry=5) +#0 different (val=6, val@entry=5) +#0 lost (val@entry=5) +#0 born (val=10) +#0 invalid (val=<optimized out>) +</pre></div> + +</dd> +<dt><code>default</code></dt> +<dd><p>Always print the actual parameter value. Print also its value from function +entry point, but only if it is known. If not in MI mode (see <a href="GDB_002fMI.html#GDB_002fMI">GDB/MI</a>) and +if both values are known and identical, print the shortened +<code>param=param@entry=VALUE</code> notation. +</p><div class="smallexample"> +<pre class="smallexample">#0 equal (val=val@entry=5) +#0 different (val=6, val@entry=5) +#0 lost (val=<optimized out>, val@entry=5) +#0 born (val=10) +#0 invalid (val=<optimized out>) +</pre></div> +</dd> +</dl> + +<p>For analysis messages on possible failures of frame argument values at function +entry resolution see <a href="Tail-Call-Frames.html#set-debug-entry_002dvalues">set debug entry-values</a>. +</p> +</dd> +<dt><code>show print entry-values</code></dt> +<dd><p>Show the method being used for printing of frame argument values at function +entry. +</p> +<a name="set-print-frame_002dinfo"></a></dd> +<dt><code>set print frame-info <var>value</var></code></dt> +<dd><a name="index-set-print-frame_002dinfo"></a> +<a name="index-printing-frame-information"></a> +<a name="index-frame-information_002c-printing"></a> +<p>This command allows to control the information printed when +the debugger prints a frame. See <a href="Frames.html#Frames">Frames</a>, <a href="Backtrace.html#Backtrace">Backtrace</a>, +for a general explanation about frames and frame information. +Note that some other settings (such as <code>set print frame-arguments</code> +and <code>set print address</code>) are also influencing if and how some frame +information is displayed. In particular, the frame program counter is never +printed if <code>set print address</code> is off. +</p> +<p>The possible values for <code>set print frame-info</code> are: +</p><dl compact="compact"> +<dt><code>short-location</code></dt> +<dd><p>Print the frame level, the program counter (if not at the +beginning of the location source line), the function, the function +arguments. +</p></dd> +<dt><code>location</code></dt> +<dd><p>Same as <code>short-location</code> but also print the source file and source line +number. +</p></dd> +<dt><code>location-and-address</code></dt> +<dd><p>Same as <code>location</code> but print the program counter even if located at the +beginning of the location source line. +</p></dd> +<dt><code>source-line</code></dt> +<dd><p>Print the program counter (if not at the beginning of the location +source line), the line number and the source line. +</p></dd> +<dt><code>source-and-location</code></dt> +<dd><p>Print what <code>location</code> and <code>source-line</code> are printing. +</p></dd> +<dt><code>auto</code></dt> +<dd><p>The information printed for a frame is decided automatically +by the <small>GDB</small> command that prints a frame. +For example, <code>frame</code> prints the information printed by +<code>source-and-location</code> while <code>stepi</code> will switch between +<code>source-line</code> and <code>source-and-location</code> depending on the program +counter. +The default value is <code>auto</code>. +</p></dd> +</dl> + +<a name="set-print-repeats"></a></dd> +<dt><code>set print repeats <var>number-of-repeats</var></code></dt> +<dt><code>set print repeats unlimited</code></dt> +<dd><a name="index-repeated-array-elements"></a> +<p>Set the threshold for suppressing display of repeated array +elements. When the number of consecutive identical elements of an +array exceeds the threshold, <small>GDB</small> prints the string +<code>"<repeats <var>n</var> times>"</code>, where <var>n</var> is the number of +identical repetitions, instead of displaying the identical elements +themselves. Setting the threshold to <code>unlimited</code> or zero will +cause all elements to be individually printed. The default threshold +is 10. +</p> +</dd> +<dt><code>show print repeats</code></dt> +<dd><p>Display the current threshold for printing repeated identical +elements. +</p> +<a name="set-print-max_002ddepth"></a></dd> +<dt><code>set print max-depth <var>depth</var></code></dt> +<dt><code>set print max-depth unlimited</code></dt> +<dd><a name="index-printing-nested-structures"></a> +<p>Set the threshold after which nested structures are replaced with +ellipsis, this can make visualising deeply nested structures easier. +</p> +<p>For example, given this C code +</p> +<div class="smallexample"> +<pre class="smallexample">typedef struct s1 { int a; } s1; +typedef struct s2 { s1 b; } s2; +typedef struct s3 { s2 c; } s3; +typedef struct s4 { s3 d; } s4; + +s4 var = { { { { 3 } } } }; +</pre></div> + +<p>The following table shows how different values of <var>depth</var> will +effect how <code>var</code> is printed by <small>GDB</small>: +</p> +<table> +<thead><tr><th width="30%"><var>depth</var> setting</th><th width="70%">Result of ‘<samp>p var</samp>’</th></tr></thead> +<tr><td width="30%">unlimited</td><td width="70%"><code>$1 = {d = {c = {b = {a = 3}}}}</code></td></tr> +<tr><td width="30%"><code>0</code></td><td width="70%"><code>$1 = {...}</code></td></tr> +<tr><td width="30%"><code>1</code></td><td width="70%"><code>$1 = {d = {...}}</code></td></tr> +<tr><td width="30%"><code>2</code></td><td width="70%"><code>$1 = {d = {c = {...}}}</code></td></tr> +<tr><td width="30%"><code>3</code></td><td width="70%"><code>$1 = {d = {c = {b = {...}}}}</code></td></tr> +<tr><td width="30%"><code>4</code></td><td width="70%"><code>$1 = {d = {c = {b = {a = 3}}}}</code></td></tr> +</table> + +<p>To see the contents of structures that have been hidden the user can +either increase the print max-depth, or they can print the elements of +the structure that are visible, for example +</p> +<div class="smallexample"> +<pre class="smallexample">(gdb) set print max-depth 2 +(gdb) p var +$1 = {d = {c = {...}}} +(gdb) p var.d +$2 = {c = {b = {...}}} +(gdb) p var.d.c +$3 = {b = {a = 3}} +</pre></div> + +<p>The pattern used to replace nested structures varies based on +language, for most languages <code>{...}</code> is used, but Fortran uses +<code>(...)</code>. +</p> +</dd> +<dt><code>show print max-depth</code></dt> +<dd><p>Display the current threshold after which nested structures are +replaces with ellipsis. +</p> +<a name="set-print-memory_002dtag_002dviolations"></a><a name="index-printing-memory-tag-violation-information"></a> +</dd> +<dt><code>set print memory-tag-violations</code></dt> +<dt><code>set print memory-tag-violations on</code></dt> +<dd><p>Cause <small>GDB</small> to display additional information about memory tag violations +when printing pointers and addresses. +</p> +</dd> +<dt><code>set print memory-tag-violations off</code></dt> +<dd><p>Stop printing memory tag violation information. +</p> +</dd> +<dt><code>show print memory-tag-violations</code></dt> +<dd><p>Show whether memory tag violation information is displayed when printing +pointers and addresses. +</p> +<a name="set-print-null_002dstop"></a></dd> +<dt><code>set print null-stop</code></dt> +<dd><a name="index-NULL-elements-in-arrays"></a> +<p>Cause <small>GDB</small> to stop printing the characters of an array when the first +<small>NULL</small> is encountered. This is useful when large arrays actually +contain only short strings. +The default is off. +</p> +</dd> +<dt><code>show print null-stop</code></dt> +<dd><p>Show whether <small>GDB</small> stops printing an array on the first +<small>NULL</small> character. +</p> +<a name="set-print-pretty"></a></dd> +<dt><code>set print pretty on</code></dt> +<dd><a name="index-print-structures-in-indented-form"></a> +<a name="index-indentation-in-structure-display"></a> +<p>Cause <small>GDB</small> to print structures in an indented format with one member +per line, like this: +</p> +<div class="smallexample"> +<pre class="smallexample">$1 = { + next = 0x0, + flags = { + sweet = 1, + sour = 1 + }, + meat = 0x54 "Pork" +} +</pre></div> + +</dd> +<dt><code>set print pretty off</code></dt> +<dd><p>Cause <small>GDB</small> to print structures in a compact format, like this: +</p> +<div class="smallexample"> +<pre class="smallexample">$1 = {next = 0x0, flags = {sweet = 1, sour = 1}, \ +meat = 0x54 "Pork"} +</pre></div> + +<p>This is the default format. +</p> +</dd> +<dt><code>show print pretty</code></dt> +<dd><p>Show which format <small>GDB</small> is using to print structures. +</p> +<a name="set-print-raw_002dvalues"></a></dd> +<dt><code>set print raw-values on</code></dt> +<dd><p>Print values in raw form, without applying the pretty +printers for the value. +</p> +</dd> +<dt><code>set print raw-values off</code></dt> +<dd><p>Print values in pretty-printed form, if there is a pretty-printer +for the value (see <a href="Pretty-Printing.html#Pretty-Printing">Pretty Printing</a>), +otherwise print the value in raw form. +</p> +<p>The default setting is “off”. +</p> +</dd> +<dt><code>show print raw-values</code></dt> +<dd><p>Show whether to print values in raw form. +</p> +</dd> +<dt><code>set print sevenbit-strings on</code></dt> +<dd><a name="index-eight_002dbit-characters-in-strings"></a> +<a name="index-octal-escapes-in-strings"></a> +<p>Print using only seven-bit characters; if this option is set, +<small>GDB</small> displays any eight-bit characters (in strings or +character values) using the notation <code>\</code><var>nnn</var>. This setting is +best if you are working in English (<small>ASCII</small>) and you use the +high-order bit of characters as a marker or “meta” bit. +</p> +</dd> +<dt><code>set print sevenbit-strings off</code></dt> +<dd><p>Print full eight-bit characters. This allows the use of more +international character sets, and is the default. +</p> +</dd> +<dt><code>show print sevenbit-strings</code></dt> +<dd><p>Show whether or not <small>GDB</small> is printing only seven-bit characters. +</p> +<a name="set-print-union"></a></dd> +<dt><code>set print union on</code></dt> +<dd><a name="index-unions-in-structures_002c-printing"></a> +<p>Tell <small>GDB</small> to print unions which are contained in structures +and other unions. This is the default setting. +</p> +</dd> +<dt><code>set print union off</code></dt> +<dd><p>Tell <small>GDB</small> not to print unions which are contained in +structures and other unions. <small>GDB</small> will print <code>"{...}"</code> +instead. +</p> +</dd> +<dt><code>show print union</code></dt> +<dd><p>Ask <small>GDB</small> whether or not it will print unions which are contained in +structures and other unions. +</p> +<p>For example, given the declarations +</p> +<div class="smallexample"> +<pre class="smallexample">typedef enum {Tree, Bug} Species; +typedef enum {Big_tree, Acorn, Seedling} Tree_forms; +typedef enum {Caterpillar, Cocoon, Butterfly} + Bug_forms; + +struct thing { + Species it; + union { + Tree_forms tree; + Bug_forms bug; + } form; +}; + +struct thing foo = {Tree, {Acorn}}; +</pre></div> + +<p>with <code>set print union on</code> in effect ‘<samp>p foo</samp>’ would print +</p> +<div class="smallexample"> +<pre class="smallexample">$1 = {it = Tree, form = {tree = Acorn, bug = Cocoon}} +</pre></div> + +<p>and with <code>set print union off</code> in effect it would print +</p> +<div class="smallexample"> +<pre class="smallexample">$1 = {it = Tree, form = {...}} +</pre></div> + +<p><code>set print union</code> affects programs written in C-like languages +and in Pascal. +</p></dd> +</dl> + +<p>These settings are of interest when debugging C<tt>++</tt> programs: +</p> +<dl compact="compact"> +<dd><a name="index-demangling-C_002b_002b-names"></a> +</dd> +<dt><code>set print demangle</code></dt> +<dt><code>set print demangle on</code></dt> +<dd><p>Print C<tt>++</tt> names in their source form rather than in the encoded +(“mangled”) form passed to the assembler and linker for type-safe +linkage. The default is on. +</p> +</dd> +<dt><code>show print demangle</code></dt> +<dd><p>Show whether C<tt>++</tt> names are printed in mangled or demangled form. +</p> +</dd> +<dt><code>set print asm-demangle</code></dt> +<dt><code>set print asm-demangle on</code></dt> +<dd><p>Print C<tt>++</tt> names in their source form rather than their mangled form, even +in assembler code printouts such as instruction disassemblies. +The default is off. +</p> +</dd> +<dt><code>show print asm-demangle</code></dt> +<dd><p>Show whether C<tt>++</tt> names in assembly listings are printed in mangled +or demangled form. +</p> +<a name="index-C_002b_002b-symbol-decoding-style"></a> +<a name="index-symbol-decoding-style_002c-C_002b_002b"></a> +<a name="index-set-demangle_002dstyle"></a> +</dd> +<dt><code>set demangle-style <var>style</var></code></dt> +<dd><p>Choose among several encoding schemes used by different compilers to represent +C<tt>++</tt> names. If you omit <var>style</var>, you will see a list of possible +formats. The default value is <var>auto</var>, which lets <small>GDB</small> choose a +decoding style by inspecting your program. +</p> +</dd> +<dt><code>show demangle-style</code></dt> +<dd><p>Display the encoding style currently in use for decoding C<tt>++</tt> symbols. +</p> +<a name="set-print-object"></a></dd> +<dt><code>set print object</code></dt> +<dt><code>set print object on</code></dt> +<dd><a name="index-derived-type-of-an-object_002c-printing"></a> +<a name="index-display-derived-types"></a> +<p>When displaying a pointer to an object, identify the <em>actual</em> +(derived) type of the object rather than the <em>declared</em> type, using +the virtual function table. Note that the virtual function table is +required—this feature can only work for objects that have run-time +type identification; a single virtual method in the object’s declared +type is sufficient. Note that this setting is also taken into account when +working with variable objects via MI (see <a href="GDB_002fMI.html#GDB_002fMI">GDB/MI</a>). +</p> +</dd> +<dt><code>set print object off</code></dt> +<dd><p>Display only the declared type of objects, without reference to the +virtual function table. This is the default setting. +</p> +</dd> +<dt><code>show print object</code></dt> +<dd><p>Show whether actual, or declared, object types are displayed. +</p> +<a name="set-print-static_002dmembers"></a></dd> +<dt><code>set print static-members</code></dt> +<dt><code>set print static-members on</code></dt> +<dd><a name="index-static-members-of-C_002b_002b-objects"></a> +<p>Print static members when displaying a C<tt>++</tt> object. The default is on. +</p> +</dd> +<dt><code>set print static-members off</code></dt> +<dd><p>Do not print static members when displaying a C<tt>++</tt> object. +</p> +</dd> +<dt><code>show print static-members</code></dt> +<dd><p>Show whether C<tt>++</tt> static members are printed or not. +</p> +</dd> +<dt><code>set print pascal_static-members</code></dt> +<dt><code>set print pascal_static-members on</code></dt> +<dd><a name="index-static-members-of-Pascal-objects"></a> +<a name="index-Pascal-objects_002c-static-members-display"></a> +<p>Print static members when displaying a Pascal object. The default is on. +</p> +</dd> +<dt><code>set print pascal_static-members off</code></dt> +<dd><p>Do not print static members when displaying a Pascal object. +</p> +</dd> +<dt><code>show print pascal_static-members</code></dt> +<dd><p>Show whether Pascal static members are printed or not. +</p> +<a name="set-print-vtbl"></a></dd> +<dt><code>set print vtbl</code></dt> +<dt><code>set print vtbl on</code></dt> +<dd><a name="index-pretty-print-C_002b_002b-virtual-function-tables"></a> +<a name="index-virtual-functions-_0028C_002b_002b_0029-display"></a> +<a name="index-VTBL-display"></a> +<p>Pretty print C<tt>++</tt> virtual function tables. The default is off. +(The <code>vtbl</code> commands do not work on programs compiled with the HP +ANSI C<tt>++</tt> compiler (<code>aCC</code>).) +</p> +</dd> +<dt><code>set print vtbl off</code></dt> +<dd><p>Do not pretty print C<tt>++</tt> virtual function tables. +</p> +</dd> +<dt><code>show print vtbl</code></dt> +<dd><p>Show whether C<tt>++</tt> virtual function tables are pretty printed, or not. +</p></dd> +</dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Pretty-Printing.html#Pretty-Printing" accesskey="n" rel="next">Pretty Printing</a>, Previous: <a href="Auto-Display.html#Auto-Display" accesskey="p" rel="previous">Auto Display</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</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> +</div> + + + +</body> +</html> |