| <html lang="en"> |
| <head> |
| <title>Data - 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="prev" href="Source.html#Source" title="Source"> |
| <link rel="next" href="Optimized-Code.html#Optimized-Code" title="Optimized Code"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, |
| 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 |
| 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> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Data"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Optimized-Code.html#Optimized-Code">Optimized Code</a>, |
| Previous: <a rel="previous" accesskey="p" href="Source.html#Source">Source</a>, |
| Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a> |
| <hr> |
| </div> |
| |
| <h2 class="chapter">10 Examining Data</h2> |
| |
| <p><a name="index-printing-data-489"></a><a name="index-examining-data-490"></a><a name="index-print-491"></a><a name="index-inspect-492"></a><!-- "inspect" is not quite a synonym if you are using Epoch, which we do not --> |
| <!-- document because it is nonstandard... Under Epoch it displays in a --> |
| <!-- different window or something like that. --> |
| The usual way to examine data in your program is with the <code>print</code> |
| command (abbreviated <code>p</code>), or its synonym <code>inspect</code>. It |
| evaluates and prints the value of an expression of the language your |
| program is written in (see <a href="Languages.html#Languages">Using <span class="sc">gdb</span> with Different Languages</a>). It may also print the expression using a |
| Python-based pretty-printer (see <a href="Pretty-Printing.html#Pretty-Printing">Pretty Printing</a>). |
| |
| <dl> |
| <dt><code>print </code><var>expr</var><dt><code>print /</code><var>f</var> <var>expr</var><dd><var>expr</var> is an expression (in the source language). By default the |
| value of <var>expr</var> is printed in a format appropriate to its data type; |
| you can choose a different format by specifying ‘<samp><span class="samp">/</span><var>f</var></samp>’, where |
| <var>f</var> is a letter specifying the format; see <a href="Output-Formats.html#Output-Formats">Output Formats</a>. |
| |
| <br><dt><code>print</code><dt><code>print /</code><var>f</var><dd><a name="index-reprint-the-last-value-493"></a>If you omit <var>expr</var>, <span class="sc">gdb</span> displays the last value again (from the |
| <dfn>value history</dfn>; see <a href="Value-History.html#Value-History">Value History</a>). This allows you to |
| conveniently inspect the same value in an alternative format. |
| </dl> |
| |
| <p>A more low-level way of examining data is with the <code>x</code> command. |
| It examines data in memory at a specified address and prints it in a |
| specified format. See <a href="Memory.html#Memory">Examining Memory</a>. |
| |
| <p>If you are interested in information about types, or about how the |
| fields of a struct or a class are declared, use the <code>ptype </code><var>exp</var> |
| command rather than <code>print</code>. See <a href="Symbols.html#Symbols">Examining the Symbol Table</a>. |
| |
| <ul class="menu"> |
| <li><a accesskey="1" href="Expressions.html#Expressions">Expressions</a>: Expressions |
| <li><a accesskey="2" href="Ambiguous-Expressions.html#Ambiguous-Expressions">Ambiguous Expressions</a>: Ambiguous Expressions |
| <li><a accesskey="3" href="Variables.html#Variables">Variables</a>: Program variables |
| <li><a accesskey="4" href="Arrays.html#Arrays">Arrays</a>: Artificial arrays |
| <li><a accesskey="5" href="Output-Formats.html#Output-Formats">Output Formats</a>: Output formats |
| <li><a accesskey="6" href="Memory.html#Memory">Memory</a>: Examining memory |
| <li><a accesskey="7" href="Auto-Display.html#Auto-Display">Auto Display</a>: Automatic display |
| <li><a accesskey="8" href="Print-Settings.html#Print-Settings">Print Settings</a>: Print settings |
| <li><a accesskey="9" href="Pretty-Printing.html#Pretty-Printing">Pretty Printing</a>: Python pretty printing |
| <li><a href="Value-History.html#Value-History">Value History</a>: Value history |
| <li><a href="Convenience-Vars.html#Convenience-Vars">Convenience Vars</a>: Convenience variables |
| <li><a href="Registers.html#Registers">Registers</a>: Registers |
| <li><a href="Floating-Point-Hardware.html#Floating-Point-Hardware">Floating Point Hardware</a>: Floating point hardware |
| <li><a href="Vector-Unit.html#Vector-Unit">Vector Unit</a>: Vector Unit |
| <li><a href="OS-Information.html#OS-Information">OS Information</a>: Auxiliary data provided by operating system |
| <li><a href="Memory-Region-Attributes.html#Memory-Region-Attributes">Memory Region Attributes</a>: Memory region attributes |
| <li><a href="Dump_002fRestore-Files.html#Dump_002fRestore-Files">Dump/Restore Files</a>: Copy between memory and a file |
| <li><a href="Core-File-Generation.html#Core-File-Generation">Core File Generation</a>: Cause a program dump its core |
| <li><a href="Character-Sets.html#Character-Sets">Character Sets</a>: Debugging programs that use a different |
| character set than GDB does |
| <li><a href="Caching-Remote-Data.html#Caching-Remote-Data">Caching Remote Data</a>: Data caching for remote targets |
| <li><a href="Searching-Memory.html#Searching-Memory">Searching Memory</a>: Searching memory for a sequence of bytes |
| </ul> |
| |
| </body></html> |
| |