cppcheck/man/manual.docbook

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<book>
  <bookinfo>
    <title>Cppcheck 1.61 dev</title>

    <date>2013-07-14</date>
  </bookinfo>

  <chapter>
    <title>Introduction</title>

    <para>Cppcheck is an analysis tool for C/C++ code. Unlike C/C++ compilers
    and many other analysis tools, it doesn't detect syntax errors. Cppcheck
    only detects the types of bugs that the compilers normally fail to detect.
    The goal is no false positives.</para>

    <para>Supported code and platforms:</para>

    <itemizedlist>
      <listitem>
        <para>You can check non-standard code that includes various compiler
        extensions, inline assembly code, etc.</para>
      </listitem>

      <listitem>
        <para>Cppcheck should be compilable by any C++ compiler that handles
        the latest C++ standard.</para>
      </listitem>

      <listitem>
        <para>Cppcheck should work on any platform that has sufficient CPU and
        memory.</para>
      </listitem>
    </itemizedlist>

    <para>Accuracy</para>

    <para>Please understand that there are limits of Cppcheck. Cppcheck is
    rarely wrong about reported errors. But there are many bugs that it
    doesn't detect.</para>

    <para>You will find more bugs in your software by testing your software
    carefully, than by using Cppcheck. You will find more bugs in your
    software by instrumenting your software, than by using Cppcheck. But
    Cppcheck can still detect some of the bugs that you miss when testing and
    instrumenting your software.</para>
  </chapter>

  <chapter>
    <title>Getting started</title>

    <section>
      <title>First test</title>

      <para>Here is a simple code</para>

      <programlisting>int main()
{
    char a[10];
    a[10] = 0;
    return 0;
}</programlisting>

      <para>If you save that into <filename>file1.c</filename> and
      execute:</para>

      <programlisting>cppcheck file1.c</programlisting>

      <para>The output from cppcheck will then be:</para>

      <programlisting>Checking file1.c...
[file1.c:4]: (error) Array 'a[10]' index 10 out of bounds</programlisting>
    </section>

    <section>
      <title>Checking all files in a folder</title>

      <para>Normally a program has many source files. And you want to check
      them all. Cppcheck can check all source files in a directory:</para>

      <programlisting>cppcheck path</programlisting>

      <para>If "path" is a folder then cppcheck will check all source files in
      this folder.</para>

      <programlisting>Checking path/file1.cpp...
1/2 files checked 50% done
Checking path/file2.cpp...
2/2 files checked 100% done</programlisting>
    </section>

    <section>
      <title>Excluding a file or folder from checking</title>

      <para>To exclude a file or folder, there are two options.</para>

      <para>The first option is to only provide the paths and files you want
      to check.</para>

      <programlisting>cppcheck src/a src/b</programlisting>

      <para>All files under <filename class="directory">src/a</filename> and
      <filename class="directory">src/b</filename> are then checked.</para>

      <para>The second option is to use <parameter
      class="command">-i</parameter>, with it you specify files/paths to
      ignore. With this command no files in <filename
      class="directory">src/c</filename> are checked:</para>

      <programlisting>cppcheck -isrc/c src</programlisting>
    </section>

    <section>
      <title>Severities</title>

      <para>The possible severities for messages are:</para>

      <variablelist>
        <varlistentry>
          <term>error</term>

          <listitem>
            <para>used when bugs are found</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>warning</term>

          <listitem>
            <para>suggestions about defensive programming to prevent
            bugs</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>style</term>

          <listitem>
            <para>stylistic issues related to code cleanup (unused functions,
            redundant code, constness, and such)</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>performance</term>

          <listitem>
            <para>Suggestions for making the code faster. These suggestions
            are only based on common knowledge. It is not certain you'll get
            any measurable difference in speed by fixing these
            messages.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>portability</term>

          <listitem>
            <para>portability warnings. 64-bit portability. code might work
            different on different compilers. etc.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>information</term>

          <listitem>
            <para>Informational messages about checking problems.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </section>

    <section>
      <title>Enable messages</title>

      <para>By default only <parameter class="command">error</parameter>
      messages are shown. Through the <parameter
      class="command">--enable</parameter> command more checks can be
      enabled.</para>

      <programlisting># enable warning messages
cppcheck --enable=warning file.c

# enable performance messages
cppcheck --enable=performance file.c

# enable information messages
cppcheck --enable=information file.c

# For historical reasons, --enable=style enables warning, performance,
# portability and style messages. These are all reported as "style" when
# using the old xml format.
cppcheck --enable=style file.c

# enable warning and information messages
cppcheck --enable=warning,information file.c

# enable unusedFunction checking. This is not enabled by --enable=style
# because it doesn't work well on libraries.
cppcheck --enable=unusedFunction file.c

# enable all messages
cppcheck --enable=all</programlisting>

      <para>Please note that <literal>--enable=unusedFunction</literal> should
      only be used when the whole program is scanned. And therefore
      <literal>--enable=all</literal> should also only be used when the whole
      program is scanned. The reason is that the unusedFunction checking will
      warn if a function is not called. There will be noise if function calls
      are not seen.</para>

      <section>
        <title>Inconclusive checks</title>

        <para>By default Cppcheck only writes error messages if it is certain.
        With <parameter class="command">--inconclusive</parameter> error
        messages will also be written when the analysis is
        inconclusive.</para>

        <programlisting>cppcheck --inconclusive path</programlisting>

        <para>This can of course cause false warnings, it might be reported
        that there are bugs even though there are not. Only use this command
        if false warnings are acceptable.</para>
      </section>
    </section>

    <section>
      <title>Saving results in file</title>

      <para>Many times you will want to save the results in a file. You can
      use the normal shell redirection for piping error output to a
      file.</para>

      <programlisting>cppcheck file1.c 2&gt; err.txt</programlisting>
    </section>

    <section>
      <title>Multithreaded checking</title>

      <para>The option -j is used to specify the number of threads you want to
      use. For example, to use 4 threads to check the files in a
      folder:</para>

      <programlisting>cppcheck -j 4 path</programlisting>
    </section>
  </chapter>

  <chapter id="preprocessor-configurations">
    <title>Preprocessor configurations</title>

    <para>By default Cppcheck will check all preprocessor configurations
    (except those that have #error in them).</para>

    <para>You can use -D to change this. When you use -D, cppcheck will by
    default only check the given configuration and nothing else. This is how
    compilers work. But you can use <literal>--force</literal> or
    <literal><literal>--max-configs</literal></literal> to override the number
    of configurations.</para>

    <programlisting># check all configurations
cppcheck file.c

# only check the configuration A
cppcheck -DA file.c

# check all configurations when macro A is defined
cppcheck -DA --force file.c</programlisting>

    <para>Another useful flag might be -U. It undefines a symbol. Example
    usage:</para>

    <programlisting>cppcheck -UX file.c</programlisting>

    <para>That will mean that X is not defined. Cppcheck will not check what
    happens when X is defined.</para>
  </chapter>

  <chapter>
    <title>XML output</title>

    <para>Cppcheck can generate the output in <literal>XML</literal> format.
    There is an old <literal>XML</literal> format (version 1) and a new
    <literal>XML</literal> format (version 2). Please use the new version if
    you can.</para>

    <para>The old version is kept for backwards compatibility only. It will
    not be changed. But it will likely be removed someday. Use
    <parameter>--xml</parameter> to enable this format.</para>

    <para>The new version fixes a few problems with the old format. The new
    format will probably be updated in future versions of cppcheck with new
    attributes and elements. A sample command to check a file and output
    errors in the new <literal>XML</literal> format:</para>

    <para><programlisting>cppcheck --xml-version=2 file1.cpp</programlisting>Here
    is a sample version 2 report:</para>

    <programlisting>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;results version="2"&gt;
  &lt;cppcheck version="1.53"&gt;
  &lt;errors&gt;
    &lt;error id="someError" severity="error" msg="short error text"
           verbose="long error text" inconclusive="true"&gt;
      &lt;location file="file.c" line="1"/&gt;
    &lt;/error&gt;
  &lt;/errors&gt;
&lt;/results&gt;</programlisting>

    <section>
      <title>The &lt;error&gt; element</title>

      <para>Each error is reported in a <literal>&lt;error&gt;</literal>
      element. Attributes:</para>

      <variablelist>
        <varlistentry>
          <term><sgmltag class="attribute">id</sgmltag></term>

          <listitem>
            <para>id of error. These are always valid symbolnames.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><sgmltag class="attribute">severity</sgmltag></term>

          <listitem>
            <para>either: <literal>error</literal>,
            <literal>warning</literal>, <literal>style</literal>,
            <literal>performance</literal>, <literal>portability</literal> or
            <literal>information</literal></para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><sgmltag class="attribute">msg</sgmltag></term>

          <listitem>
            <para>the error message in short format</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><sgmltag>verbose</sgmltag></term>

          <listitem>
            <para>the error message in long format.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><sgmltag>inconclusive</sgmltag></term>

          <listitem>
            <para>This attribute is only used when the message is
            inconclusive.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </section>

    <section>
      <title>The &lt;location&gt; element</title>

      <para>All locations related to an error is listed with
      <literal>&lt;location&gt;</literal> elements. The primary location is
      listed first.</para>

      <para>Attributes:</para>

      <variablelist>
        <varlistentry>
          <term><sgmltag class="attribute">file</sgmltag></term>

          <listitem>
            <para>filename. Both relative and absolute paths are
            possible</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><sgmltag class="attribute">line</sgmltag></term>

          <listitem>
            <para>a number</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><sgmltag>msg</sgmltag></term>

          <listitem>
            <para>this attribute doesn't exist yet. But in the future we may
            add a short message for each location.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </section>
  </chapter>

  <chapter>
    <title>Reformatting the output</title>

    <para>If you want to reformat the output so it looks different you can use
    templates.</para>

    <para>To get Visual Studio compatible output you can use <parameter
    class="command">--template=vs</parameter>:</para>

    <programlisting>cppcheck --template=vs gui/test.cpp</programlisting>

    <para>This output will look like this:</para>

    <programlisting>Checking gui/test.cpp...
gui/test.cpp(31): error: Memory leak: b
gui/test.cpp(16): error: Mismatching allocation and deallocation: k</programlisting>

    <para>To get gcc compatible output you can use <parameter
    class="command">--template=gcc</parameter>:</para>

    <programlisting>cppcheck --template=gcc gui/test.cpp</programlisting>

    <para>The output will look like this:</para>

    <programlisting>Checking gui/test.cpp...
gui/test.cpp:31: error: Memory leak: b
gui/test.cpp:16: error: Mismatching allocation and deallocation: k</programlisting>

    <para>You can write your own pattern (for example a comma-separated
    format):</para>

    <programlisting>cppcheck --template="{file},{line},{severity},{id},{message}" gui/test.cpp</programlisting>

    <para>The output will look like this:</para>

    <programlisting>Checking gui/test.cpp...
gui/test.cpp,31,error,memleak,Memory leak: b
gui/test.cpp,16,error,mismatchAllocDealloc,Mismatching allocation and deallocation: k</programlisting>

    <para>The following format specifiers are supported:</para>

    <variablelist>
      <varlistentry>
        <term>callstack</term>

        <listitem>
           callstack - if available 
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>file</term>

        <listitem>
           filename 
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>id</term>

        <listitem>
           message id 
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>line</term>

        <listitem>
           line number 
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>message</term>

        <listitem>
           verbose message text 
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>severity</term>

        <listitem>
           severity 
        </listitem>
      </varlistentry>
    </variablelist>

    <para>The escape sequences \b (backspace), \n (newline), \r (formfeed) and
    \t (horizontal tab) are supported.</para>
  </chapter>

  <chapter>
    <title>Suppressions</title>

    <para>If you want to filter out certain errors you can suppress
    these.</para>

    <section>
      <title>Suppressing a certain error type</title>

      <para>You can suppress certain types of errors. The format for such a
      suppression is one of:</para>

      <programlisting>[error id]:[filename]:[line]
[error id]:[filename2]
[error id]</programlisting>

      <para>The <replaceable>error id</replaceable> is the id that you want to
      suppress. The easiest way to get it is to use the <parameter
      class="command">--xml</parameter> command line flag. Copy and paste the
      <replaceable>id</replaceable> string from the XML output. This may be
      <literal>*</literal> to suppress all warnings (for a specified file or
      files).</para>

      <para>The <replaceable>filename</replaceable> may include the wildcard
      characters <literal>*</literal> or <literal>?</literal>, which match any
      sequence of characters or any single character respectively. It is
      recommended that you use "/" as path separator on all operating
      systems.</para>

      <section>
        <title>Command line suppression</title>

        <para>The <parameter class="command">--suppress=</parameter> command
        line option is used to specify suppressions on the command line.
        Example:</para>

        <programlisting>cppcheck --suppress=memleak:src/file1.cpp src/</programlisting>
      </section>

      <section>
        <title>Listing suppressions in a file</title>

        <para>You can create a suppressions file. Example:</para>

        <programlisting>// suppress memleak and exceptNew errors in the file src/file1.cpp
memleak:src/file1.cpp
exceptNew:src/file1.cpp

// suppress all uninitvar errors in all files
uninitvar</programlisting>

        <para>Note that you may add empty lines and comments in the
        suppressions file.</para>

        <para>You can use the suppressions file like this:</para>

        <programlisting>cppcheck --suppressions suppressions.txt src/</programlisting>
      </section>
    </section>

    <section>
      <title>Inline suppressions</title>

      <para>Suppressions can also be added directly in the code by adding
      comments that contain special keywords. Before adding such comments,
      consider that the code readability is sacrificed a little.</para>

      <para>This code will normally generate an error message:</para>

      <programlisting>void f() {
    char arr[5];
    arr[10] = 0;
}</programlisting>

      <para>The output is:</para>

      <programlisting># cppcheck test.c
Checking test.c...
[test.c:3]: (error) Array 'arr[5]' index 10 out of bounds</programlisting>

      <para>To suppress the error message, a comment can be added:</para>

      <programlisting>void f() {
    char arr[5];

    // cppcheck-suppress arrayIndexOutOfBounds
    arr[10] = 0;
}</programlisting>

      <para>Now the --inline-suppr flag can be used to suppress the warning.
      No error is reported when invoking cppcheck this way:</para>

      <programlisting>cppcheck --inline-suppr test.c</programlisting>
    </section>
  </chapter>

  <chapter>
    <title>Rules</title>

    <para>You can define custom rules using regular expressions.</para>

    <para>These rules can not perform sophisticated analysis of the code. But
    they give you an easy way to check for various simple patterns in the
    code.</para>

    <para>To get started writing rules, see the related articles here:</para>

    <para><uri>http://sourceforge.net/projects/cppcheck/files/Articles/</uri></para>

    <para>The file format for rules is:</para>

    <programlisting>&lt;?xml version="1.0"?&gt;
&lt;rule&gt;
  &lt;tokenlist&gt;LIST&lt;/tokenlist&gt;
  &lt;pattern&gt;PATTERN&lt;/pattern&gt;
  &lt;message&gt;
    &lt;id&gt;ID&lt;/id&gt;
    &lt;severity&gt;SEVERITY&lt;/severity&gt;
    &lt;summary&gt;SUMMARY&lt;/summary&gt;
  &lt;/message&gt;
&lt;/rule&gt;</programlisting>

    <section>
      <title>&lt;tokenlist&gt;</title>

      <para>The <literal>&lt;tokenlist&gt;</literal> element is optional. With
      this element you can control what tokens are checked. The
      <literal>LIST</literal> can be either <literal>define</literal>,
      <literal>raw</literal>, <literal>normal</literal> or
      <literal>simple</literal>.</para>

      <variablelist>
        <varlistentry>
          <term>define</term>

          <listitem>
            <para>used to check #define preprocessor statements.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>raw</term>

          <listitem>
            <para>used to check the preprocessor output.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>normal</term>

          <listitem>
            <para>used to check the <literal>normal</literal> token list.
            There are some simplifications.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>simple</term>

          <listitem>
            <para>used to check the simple token list. All simplifications are
            used. Most Cppcheck checks use the simple token list.</para>
          </listitem>
        </varlistentry>
      </variablelist>

      <para>If there is no &lt;tokenlist&gt; element then
      <literal>simple</literal> is used automatically.</para>
    </section>

    <section>
      <title>&lt;pattern&gt;</title>

      <para>The <literal>PATTERN</literal> is the
      <literal>PCRE</literal>-compatible regular expression that will be
      executed.</para>
    </section>

    <section>
      <title>&lt;id&gt;</title>

      <para>The ID specify the user-defined message id.</para>
    </section>

    <section>
      <title>&lt;severity&gt;</title>

      <para>The <literal>SEVERITY</literal> must be one of the
      <literal>Cppcheck</literal> severities: <literal>information</literal>,
      <literal>performance</literal>, <literal>portability</literal>,
      <literal>style</literal>, <literal>warning</literal>, or
      <literal>error</literal>.</para>
    </section>

    <section>
      <title>&lt;summary&gt;</title>

      <para>Optional. The summary for the message. If no summary is given, the
      matching tokens is written.</para>
    </section>
  </chapter>

  <chapter>
    <title>Library configuration</title>

    <para><literal>Cppcheck</literal> has internal knowledge about how
    standard C/C++ functions work. There is no internal knowledge about how
    all libraries and environments work, and there can't be.
    <literal>Cppcheck</literal> can be told how libraries and environments
    work by using configuration files.</para>

    <para>The idea is that users will be able to download library
    configuration files for all popular libraries and environments
    here:</para>

    <para><uri>http://cppcheck.sourceforge.net/archive</uri></para>

    <para>Ideally, all you need to do is choose and download the configuration
    files you need.</para>

    <para>The archive is not complete however. If you can't find the
    configuration file you need in the archive, you can wait - maybe somebody
    else will write it and share it. Or you can write your own configuration
    file (and then it's possible to share your configuration file with
    others).</para>

    <para>A minimal configuration file looks like this:</para>

    <programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
&lt;/def&gt;</programlisting>

    <section>
      <title>&lt;alloc&gt; and &lt;dealloc&gt;</title>

      <para>Allocation and deallocation is defined <literal>using
      &lt;alloc&gt; and &lt;dealloc&gt;. These are used inside inside
      <literal>&lt;memory&gt;</literal> or
      <literal>&lt;resource&gt;.</literal></literal></para>

      <para>Here is example code:</para>

      <programlisting>void ok()
{
    char *p = alloc_something();
    free_something(p);
}

void leak()
{
    char *p = alloc_something();
}</programlisting>

      <para>Cppcheck doesn't normally report any errors for that:</para>

      <programlisting># cppcheck test.c 
Checking test.c...</programlisting>

      <para>Example configuration:</para>

      <programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
  &lt;memory&gt;
    &lt;alloc&gt;alloc_something&lt;/alloc&gt;
    &lt;dealloc&gt;free_something&lt;/dealloc&gt;
  &lt;/memory&gt;
&lt;/def&gt;</programlisting>

      <para>That tells Cppcheck that <literal>alloc_something</literal>
      allocates memory and that the matching deallocation function is
      <literal>free_something</literal>.</para>

      <para>Output from <literal>Cppcheck</literal>:</para>

      <programlisting># cppcheck --library=something.cfg test.c 
Checking test.c...
[test.c:10]: (error) Memory leak: p</programlisting>
    </section>

    <section>
      <title>&lt;ignore&gt; and &lt;use&gt;</title>

      <para>The <literal>&lt;ignore&gt;</literal> and
      <literal>&lt;use&gt;</literal> tells Cppcheck how functions uses
      allocated memory. Example code:</para>

      <programlisting>void f()
{
    char *p = alloc_something();
    do_something(p);
    *p = 0;
}</programlisting>

      <para>If you want that the <literal>do_something</literal> function call
      is ignored, use &lt;ignore&gt;:</para>

      <programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
  &lt;memory&gt;
    &lt;alloc&gt;alloc_something&lt;/alloc&gt;
    &lt;dealloc&gt;free_something&lt;/dealloc&gt;
  &lt;/memory&gt;
  &lt;ignore&gt;do_something&lt;/ignore&gt;
&lt;/def&gt;</programlisting>

      <para>Running <literal>Cppcheck</literal> now:</para>

      <para><programlisting># cppcheck --library=something.cfg test.c 
Checking test.c...
[test.c:10]: (error) Memory leak: p</programlisting>If the
      <literal>do_something</literal> takes the allocated memory and
      deallocates it later, then use <literal>&lt;use&gt;</literal>
      instead:</para>

      <para><programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
  &lt;memory&gt;
    &lt;alloc&gt;alloc_something&lt;/alloc&gt;
    &lt;dealloc&gt;free_something&lt;/dealloc&gt;
    &lt;use&gt;do_something&lt;/use&gt;
  &lt;/memory&gt;
&lt;/def&gt;</programlisting>Running Cppcheck now:</para>

      <programlisting># cppcheck --library=something.cfg test.c 
Checking test.c...</programlisting>

      <para>Cppcheck will often assume that functions "use" allocated memory.
      By using &lt;ignore&gt; you can make Cppcheck detect more errors. By
      using &lt;use&gt;, no extra errors are detected but Cppcheck will not
      need to assume.</para>
    </section>

    <section>
      <title>allocate but not initialize</title>

      <para>Some allocation function initialize the data, others don't. Here
      is a example code:</para>

      <programlisting>void f()
{
    char *p = alloc_something();
    char c = *p;
    free_something();
}</programlisting>

      <para>No error is reported:</para>

      <programlisting># cppcheck --library=something.cfg test.c 
Checking test.c...</programlisting>

      <para>Here is a configuration that tells cppcheck that alloc_something
      doesn't initialize the data:</para>

      <programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
  &lt;memory&gt;
    &lt;alloc init="false"&gt;alloc_something&lt;/alloc&gt;
    &lt;dealloc&gt;free_something&lt;/dealloc&gt;
  &lt;/memory&gt;
&lt;/def&gt;</programlisting>

      <para>Now you will get this error message:</para>

      <programlisting># cppcheck --library=something.cfg test.c
Checking test.c...
[test.c:4]: (error) Memory is allocated but not initialized: p</programlisting>
    </section>

    <section>
      <title>function arguments: null pointers</title>

      <para>You can define if a function parameter can be NULL or if it must
      be non-NULL.</para>

      <para>Example code:</para>

      <programlisting>void do_something(char *p);

void f()
{
    do_something(NULL);
}</programlisting>

      <para>Normally no error is reported for that code.</para>

      <para>But if the do_something() parameter should be non-NULL you can use
      this configuration:</para>

      <programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
  &lt;function name="do_something"&gt;
    &lt;arg nr="1"&gt;
      &lt;not-null/&gt;
    &lt;/arg&gt;
  &lt;/function&gt;
&lt;/def&gt;</programlisting>

      <para>Now the output from cppcheck is:</para>

      <programlisting># cppcheck --library=something.cfg test1.c
Checking test1.c...
[test1.c:5]: (error) Null pointer dereference</programlisting>
    </section>

    <section>
      <title>Function arguments: uninitialized data</title>

      <para>Here is example code:</para>

      <programlisting>void do_something(char *p);

void f() 
{
    char str[10];
    do_something(str);
}</programlisting>

      <para>Normally <literal>Cppcheck</literal> doesn't report any error
      message for that. However if the parameter must be initialized there is
      a problem. Here is a configuration that says that the parameter must be
      initialized:</para>

      <para><programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
  &lt;function name="do_something"&gt;
    &lt;arg nr="1"&gt;
      &lt;not-uninit/&gt;
    &lt;/arg&gt;
  &lt;/function&gt;
&lt;/def&gt;</programlisting>Now the cppcheck output is:</para>

      <programlisting># cppcheck --library=something.cfg test1.c
Checking test1.c...
[test1.c:6]: (error) Uninitialized variable: str</programlisting>
    </section>

    <section>
      <title>no return</title>

      <para>You can define if a function is "noreturn" or not. Example
      code:</para>

      <programlisting>int f(int x)
{
    int a;
    if (x == 3)
        a = 1;
    else
        do_something();
    return a;  // a is uninitialized if do_something() is called and it returns
}</programlisting>

      <para>The output is:</para>

      <programlisting># cppcheck test.c 
Checking test.c...</programlisting>

      <para>To tell Cppcheck that <literal>do_something</literal> is not a
      <literal>noreturn</literal> function, use such configuration:</para>

      <programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
  &lt;function name="do_something"&gt;
    &lt;noreturn&gt;false&lt;/noreturn&gt;
  &lt;/function&gt;
&lt;/def&gt;</programlisting>

      <para>Now Cppcheck will be able to detect the error:</para>

      <programlisting>cppcheck --library=something.cfg test.c 
Checking test.c...
[test.c:8]: (error) Uninitialized variable: a</programlisting>
    </section>
  </chapter>

  <chapter>
    <title>HTML report</title>

    <para>You can convert the XML output from cppcheck into a HTML report.
    You'll need Python and the pygments module (<ulink
    url="http://pygments.org/">http://pygments.org/</ulink>) for this to work.
    In the Cppcheck source tree there is a folder <filename
    class="directory">htmlreport</filename> that contains a script that
    transforms a Cppcheck XML file into HTML output.</para>

    <para>This command generates the help screen:</para>

    <programlisting>htmlreport/cppcheck-htmlreport -h</programlisting>

    <para>The output screen says:</para>

    <programlisting>Usage: cppcheck-htmlreport [options]

Options:
  -h, --help      show this help message and exit
  --file=FILE     The cppcheck xml output file to read defects from.
                  Default is reading from stdin.
  --report-dir=REPORT_DIR
                  The directory where the html report content is written.
  --source-dir=SOURCE_DIR
                  Base directory where source code files can be found.</programlisting>

    <para>An example usage:</para>

    <programlisting>./cppcheck gui/test.cpp --xml 2&gt; err.xml
htmlreport/cppcheck-htmlreport --file=err.xml --report-dir=test1 --source-dir=.</programlisting>
  </chapter>

  <chapter>
    <title>Graphical user interface</title>

    <section>
      <title>Introduction</title>

      <para>A Cppcheck GUI is available.</para>

      <para>The main screen is shown immediately when the GUI is
      started.</para>
    </section>

    <section>
      <title>Check source code</title>

      <para>Use the <guimenu>Check</guimenu> menu.</para>
    </section>

    <section>
      <title>Inspecting results</title>

      <para>The results are shown in a list.</para>

      <para>You can show/hide certain types of messages through the
      <guimenu>View</guimenu> menu.</para>

      <para>Results can be saved to an XML file that can later be opened. See
      <literal>Save results to file</literal> and <literal>Open
      XML</literal>.</para>
    </section>

    <section>
      <title>Settings</title>

      <para>The language can be changed at any time by using the
      <guimenu>Language</guimenu> menu.</para>

      <para>More settings are available in <menuchoice>
          <guimenu>Edit</guimenu>

          <guimenuitem>Preferences</guimenuitem>
        </menuchoice>.</para>
    </section>

    <section>
      <title>Project files</title>

      <para>The project files are used to store project specific settings.
      These settings are:</para>

      <itemizedlist>
        <listitem>
          <para>include folders</para>
        </listitem>

        <listitem>
          <para>preprocessor defines</para>
        </listitem>
      </itemizedlist>

      <para>As you can read in <link
      linkend="preprocessor-configurations">chapter 3</link> in this manual
      the default is that Cppcheck checks all configurations. So only provide
      preprocessor defines if you want to limit the checking.</para>
    </section>
  </chapter>
</book>