<html lang="en">
<head>
<title>Gcov Data Files - Using the GNU Compiler Collection (GCC)</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Using the GNU Compiler Collection (GCC)">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="Gcov.html#Gcov" title="Gcov">
<link rel="prev" href="Gcov-and-Optimization.html#Gcov-and-Optimization" title="Gcov and Optimization">
<link rel="next" href="Cross_002dprofiling.html#Cross_002dprofiling" title="Cross-profiling">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
2008 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 1.2 or
any later version published by the Free Software Foundation; with the
Invariant Sections being ``Funding Free Software'', the Front-Cover
Texts being (a) (see below), and with the Back-Cover Texts being (b)
(see below).  A copy of the license is included in the section entitled
``GNU Free Documentation License''.

(a) The FSF's Front-Cover Text is:

     A GNU Manual

(b) The FSF's Back-Cover Text is:

     You have freedom to copy and modify this GNU Manual, like GNU
     software.  Copies published by the Free Software Foundation raise
     funds for GNU development.-->
<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="Gcov-Data-Files"></a>
<p>
Next:&nbsp;<a rel="next" accesskey="n" href="Cross_002dprofiling.html#Cross_002dprofiling">Cross-profiling</a>,
Previous:&nbsp;<a rel="previous" accesskey="p" href="Gcov-and-Optimization.html#Gcov-and-Optimization">Gcov and Optimization</a>,
Up:&nbsp;<a rel="up" accesskey="u" href="Gcov.html#Gcov">Gcov</a>
<hr>
</div>

<h3 class="section">10.4 Brief description of <samp><span class="command">gcov</span></samp> data files</h3>

<p><samp><span class="command">gcov</span></samp> uses two files for profiling.  The names of these files
are derived from the original <em>object</em> file by substituting the
file suffix with either <samp><span class="file">.gcno</span></samp>, or <samp><span class="file">.gcda</span></samp>.  All of these files
are placed in the same directory as the object file, and contain data
stored in a platform-independent format.

 <p>The <samp><span class="file">.gcno</span></samp> file is generated when the source file is compiled with
the GCC <samp><span class="option">-ftest-coverage</span></samp> option.  It contains information to
reconstruct the basic block graphs and assign source line numbers to
blocks.

 <p>The <samp><span class="file">.gcda</span></samp> file is generated when a program containing object files
built with the GCC <samp><span class="option">-fprofile-arcs</span></samp> option is executed.  A
separate <samp><span class="file">.gcda</span></samp> file is created for each object file compiled with
this option.  It contains arc transition counts, and some summary
information.

 <p>The full details of the file format is specified in <samp><span class="file">gcov-io.h</span></samp>,
and functions provided in that header file should be used to access the
coverage files.

 </body></html>