c++filt(1) — Linux manual page


C++FILT(1)                GNU Development Tools               C++FILT(1)

NAME         top

       c++filt - demangle C++ and Java symbols

SYNOPSIS         top

       c++filt [-_|--strip-underscore]
               [-s format|--format=format]
               [--help]  [--version]  [symbol...]

DESCRIPTION         top

       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 mangling. The c++filt [1] program does the
       inverse mapping: it decodes (demangles) low-level names into
       user-level names so that they can be read.

       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 c++filt
       and see the same source file containing demangled names.

       You can also use c++filt to decipher individual symbols by
       passing them on the command line:

               c++filt <symbol>

       If no symbol arguments are given, c++filt 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:

               c++filt -n _Z1fv

       will work and demangle the name to "f()" whereas:

               c++filt -n _Z1fv,

       will not work.  (Note the extra comma at the end of the mangled
       name which makes it invalid).  This command however will work:

               echo _Z1fv, | c++filt -n

       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

                   .type   _Z1fv, @function

OPTIONS         top

           On some systems, both the C and C++ compilers put an
           underscore in front of every name.  For example, the C name
           "foo" gets the low-level name "_foo".  This option removes
           the initial underscore.  Whether c++filt removes the
           underscore by default is target dependent.

           Do not remove the initial underscore.

           When demangling the name of a function, do not display the
           types of the function's parameters.

           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

           Do not include implementation details (if any) in the
           demangled output.

           Enables or disables a limit on the amount of recursion
           performed whilst demangling strings.  Since the name mangling
           formats allow for an infinite level of recursion it is
           possible to create strings whose decoding will exhaust the
           amount of stack space available on the host machine,
           triggering a memory fault.  The limit tries to prevent this
           from happening by restricting recursion to 2048 levels of

           The default is for this limit to be enabled, but disabling it
           may be necessary in order to demangle truly complicated
           names.  Note however that if the recursion limit is disabled
           then stack exhaustion is possible and any bug reports about
           such an event will be rejected.

           The -r option is a synonym for the --no-recurse-limit option.
           The -R option is a synonym for the --recurse-limit option.

       -s format
           c++filt can decode various methods of mangling, used by
           different compilers.  The argument to this option selects
           which method it uses:

               Automatic selection based on executable (the default

               the one used by the GNU C++ compiler (g++)

               the one used by the Lucid compiler (lcc)

               the one specified by the C++ Annotated Reference Manual

               the one used by the HP compiler (aCC)

               the one used by the EDG compiler

               the one used by the GNU C++ compiler (g++) with the V3

               the one used by the GNU Java compiler (gcj)

               the one used by the GNU Ada compiler (GNAT).

           Print a summary of the options to c++filt and exit.

           Print the version number of c++filt and exit.

           Read command-line options from file.  The options read are
           inserted in place of the original @file option.  If file does
           not exist, or cannot be read, then the option will be treated
           literally, and not removed.

           Options in file are separated by whitespace.  A whitespace
           character may be included in an option by surrounding the
           entire option in either single or double quotes.  Any
           character (including a backslash) may be included by
           prefixing the character to be included with a backslash.  The
           file may itself contain additional @file options; any such
           options will be processed recursively.

FOOTNOTES         top

       1.  MS-DOS does not allow "+" characters in file names, so on MS-
           DOS this program is named CXXFILT.

SEE ALSO         top

       the Info entries for binutils.

COPYRIGHT         top

       Copyright (c) 1991-2023 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 no Invariant Sections, with no Front-Cover
       Texts, and with no Back-Cover Texts.  A copy of the license is
       included in the section entitled "GNU Free Documentation

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       This page is part of the binutils (a collection of tools for
       working with executable binaries) project.  Information about the
       project can be found at ⟨http://www.gnu.org/software/binutils/⟩.
       If you have a bug report for this manual page, see
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binutils-2.41                  2023-12-22                     C++FILT(1)