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| <a name="c_002b_002bfilt"></a> |
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| <a name="c_002b_002bfilt-1"></a> |
| <h2 class="chapter">9 c++filt</h2> |
| |
| <a name="index-c_002b_002bfilt"></a> |
| <a name="index-demangling-C_002b_002b-symbols"></a> |
| |
| |
| <div class="smallexample"> |
| <pre class="smallexample">c++filt [<samp>-_</samp>|<samp>--strip-underscore</samp>] |
| [<samp>-n</samp>|<samp>--no-strip-underscore</samp>] |
| [<samp>-p</samp>|<samp>--no-params</samp>] |
| [<samp>-t</samp>|<samp>--types</samp>] |
| [<samp>-i</samp>|<samp>--no-verbose</samp>] |
| [<samp>-s</samp> <var>format</var>|<samp>--format=</samp><var>format</var>] |
| [<samp>--help</samp>] [<samp>--version</samp>] [<var>symbol</var>…] |
| </pre></div> |
| |
| |
| <a name="index-cxxfilt"></a> |
| <p>The C++ and Java languages provide function overloading, which means |
| that you can write many functions with the same name, providing that |
| each function takes parameters of different types. In order to be |
| able to distinguish these similarly named functions C++ and Java |
| encode them into a low-level assembler name which uniquely identifies |
| each different version. This process is known as <em>mangling</em>. The |
| <code>c++filt</code> |
| <a name="DOCF1" href="#FOOT1"><sup>1</sup></a> |
| program does the inverse mapping: it decodes (<em>demangles</em>) low-level |
| names into user-level names so that they can be read. |
| </p> |
| <p>Every alphanumeric word (consisting of letters, digits, underscores, |
| dollars, or periods) seen in the input is a potential mangled name. |
| If the name decodes into a C++ name, the C++ name replaces the |
| low-level name in the output, otherwise the original word is output. |
| In this way you can pass an entire assembler source file, containing |
| mangled names, through <code>c++filt</code> and see the same source file |
| containing demangled names. |
| </p> |
| <p>You can also use <code>c++filt</code> to decipher individual symbols by |
| passing them on the command line: |
| </p> |
| <div class="example"> |
| <pre class="example">c++filt <var>symbol</var> |
| </pre></div> |
| |
| <p>If no <var>symbol</var> arguments are given, <code>c++filt</code> reads symbol |
| names from the standard input instead. All the results are printed on |
| the standard output. The difference between reading names from the |
| command line versus reading names from the standard input is that |
| command line arguments are expected to be just mangled names and no |
| checking is performed to separate them from surrounding text. Thus |
| for example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">c++filt -n _Z1fv |
| </pre></div> |
| |
| <p>will work and demangle the name to “f()” whereas: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">c++filt -n _Z1fv, |
| </pre></div> |
| |
| <p>will not work. (Note the extra comma at the end of the mangled |
| name which makes it invalid). This command however will work: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">echo _Z1fv, | c++filt -n |
| </pre></div> |
| |
| <p>and will display “f(),”, i.e., the demangled name followed by a |
| trailing comma. This behaviour is because when the names are read |
| from the standard input it is expected that they might be part of an |
| assembler source file where there might be extra, extraneous |
| characters trailing after a mangled name. For example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample"> .type _Z1fv, @function |
| </pre></div> |
| |
| |
| |
| <dl compact="compact"> |
| <dt><code>-_</code></dt> |
| <dt><code>--strip-underscore</code></dt> |
| <dd><p>On some systems, both the C and C++ compilers put an underscore in front |
| of every name. For example, the C name <code>foo</code> gets the low-level |
| name <code>_foo</code>. This option removes the initial underscore. Whether |
| <code>c++filt</code> removes the underscore by default is target dependent. |
| </p> |
| </dd> |
| <dt><code>-n</code></dt> |
| <dt><code>--no-strip-underscore</code></dt> |
| <dd><p>Do not remove the initial underscore. |
| </p> |
| </dd> |
| <dt><code>-p</code></dt> |
| <dt><code>--no-params</code></dt> |
| <dd><p>When demangling the name of a function, do not display the types of |
| the function’s parameters. |
| </p> |
| </dd> |
| <dt><code>-t</code></dt> |
| <dt><code>--types</code></dt> |
| <dd><p>Attempt to demangle types as well as function names. This is disabled |
| by default since mangled types are normally only used internally in |
| the compiler, and they can be confused with non-mangled names. For example, |
| a function called “a” treated as a mangled type name would be |
| demangled to “signed char”. |
| </p> |
| </dd> |
| <dt><code>-i</code></dt> |
| <dt><code>--no-verbose</code></dt> |
| <dd><p>Do not include implementation details (if any) in the demangled |
| output. |
| </p> |
| </dd> |
| <dt><code>-s <var>format</var></code></dt> |
| <dt><code>--format=<var>format</var></code></dt> |
| <dd><p><code>c++filt</code> can decode various methods of mangling, used by |
| different compilers. The argument to this option selects which |
| method it uses: |
| </p> |
| <dl compact="compact"> |
| <dt><code>auto</code></dt> |
| <dd><p>Automatic selection based on executable (the default method) |
| </p></dd> |
| <dt><code>gnu</code></dt> |
| <dd><p>the one used by the <small>GNU</small> C++ compiler (g++) |
| </p></dd> |
| <dt><code>lucid</code></dt> |
| <dd><p>the one used by the Lucid compiler (lcc) |
| </p></dd> |
| <dt><code>arm</code></dt> |
| <dd><p>the one specified by the C++ Annotated Reference Manual |
| </p></dd> |
| <dt><code>hp</code></dt> |
| <dd><p>the one used by the HP compiler (aCC) |
| </p></dd> |
| <dt><code>edg</code></dt> |
| <dd><p>the one used by the EDG compiler |
| </p></dd> |
| <dt><code>gnu-v3</code></dt> |
| <dd><p>the one used by the <small>GNU</small> C++ compiler (g++) with the V3 ABI. |
| </p></dd> |
| <dt><code>java</code></dt> |
| <dd><p>the one used by the <small>GNU</small> Java compiler (gcj) |
| </p></dd> |
| <dt><code>gnat</code></dt> |
| <dd><p>the one used by the <small>GNU</small> Ada compiler (GNAT). |
| </p></dd> |
| </dl> |
| |
| </dd> |
| <dt><code>--help</code></dt> |
| <dd><p>Print a summary of the options to <code>c++filt</code> and exit. |
| </p> |
| </dd> |
| <dt><code>--version</code></dt> |
| <dd><p>Print the version number of <code>c++filt</code> and exit. |
| </p></dd> |
| </dl> |
| |
| |
| |
| <blockquote> |
| <p><em>Warning:</em> <code>c++filt</code> is a new utility, and the details of its |
| user interface are subject to change in future releases. In particular, |
| a command-line option may be required in the future to decode a name |
| passed as an argument on the command line; in other words, |
| </p> |
| <div class="example"> |
| <pre class="example">c++filt <var>symbol</var> |
| </pre></div> |
| |
| <p>may in a future release become |
| </p> |
| <div class="example"> |
| <pre class="example">c++filt <var>option</var> <var>symbol</var> |
| </pre></div> |
| </blockquote> |
| |
| <div class="footnote"> |
| <hr> |
| <h4 class="footnotes-heading">Footnotes</h4> |
| |
| <h3><a name="FOOT1" href="#DOCF1">(1)</a></h3> |
| <p>MS-DOS does not allow <kbd>+</kbd> characters in file names, so on |
| MS-DOS this program is named <code>CXXFILT</code>.</p> |
| </div> |
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