C++FILT(1)

✨ c++filt — the girlies' guide to demangling 💅

okay bestie, welcome to c++filt, part of the GNU Development Tools lineup. she's iconic, she's underrated, and she is about to un-gobble your unreadable symbol soup. 🍓

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🌸 NAME 🌸

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

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🎀 SYNOPSIS 🎀

c++filt [-_|--strip-underscore]
        [-n|--no-strip-underscore]
        [-p|--no-params]
        [-t|--types]
        [-i|--no-verbose]
        [-r|--no-recurse-limit]
        [-R|--recurse-limit]
        [-s format|--format=format]
        [--help]  [--version]  [symbol...]

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💖 DESCRIPTION 💖

so. C++ and Java both do this thing called function overloading, which lowkey means you can write a whole bunch of functions with the exact same name, as long as each one takes parameters of different types. cute, right? but it creates a problem: how does the compiler tell them apart down at the assembler level?? 🫠

the answer is mangling — C++ and Java encode each function into a low-level assembler name that uniquely identifies every single different version. it's giving fake identity. 🙈

and c++filt [1] does the inverse mapping: she decodes (demangles) those low-level names back into user-level names so actual humans can read them. she's the translator at the function, fr fr.

every alphanumeric word (that means letters, digits, underscores, dollars, or periods) that shows up in the input is a potential mangled name. if the name decodes into a C++ name, then boom — the C++ name replaces the low-level name in the output. if it doesn't decode, the original word just gets printed as-is, no drama. so you can literally pipe an entire assembler source file full of mangled names through c++filt and get the same source file back, just with demangled names. slay. ✨

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

c++filt <symbol>

if you give her no symbol arguments at all, c++filt reads symbol names from standard input instead. all the results go out on standard output. 💫

now here's the tea: reading names from the command line versus reading them from standard input is not the same vibe. command-line arguments are expected to be just mangled names, and no checking is performed to separate them from surrounding text. so for example:

c++filt -n _Z1fv

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

c++filt -n _Z1fv,

will not work. (note the extra comma at the end of the mangled name — that makes it invalid, bestie. 💀)

this command, however, will work:

echo _Z1fv, | c++filt -n

and will display "f(),", i.e. the demangled name followed by a trailing comma. why the difference? because when names are read from standard input, it's expected that they might be part of an assembler source file, where there might be extra, extraneous characters trailing after a mangled name. like this:

    .type   _Z1fv, @function

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✨ OPTIONS ✨

• -_, --strip-underscore — on some systems, both the C and C++ compilers stick an underscore in front of every name. for example, the C name "foo" gets the low-level name "_foo". this option removes that initial underscore. whether c++filt removes the underscore by default is target dependent (iykyk).
• -n, --no-strip-underscore — do not remove the initial underscore. leave it be. 🫶
• -p, --no-params — when demangling a function's name, don't display the types of the function's parameters. keeping it minimal.
• -t, --types — 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 get confused with non-mangled names. for example, a function called "a" treated as a mangled type name would be demangled to "signed char". 😭 chaos.
• -i, --no-verbose — don't include implementation details (if any) in the demangled output.
• -r, -R, --recurse-limit, --no-recurse-limit, --recursion-limit, --no-recursion-limit — enables or disables a limit on how much recursion happens while demangling strings. since the name mangling formats allow for an infinite level of recursion, it's 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 stop that from happening by restricting recursion to 2048 levels of nesting. 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, --format=format — c++filt can decode various methods of mangling, used by different compilers. the argument to this option selects which method she uses:
  • "auto" — automatic selection based on executable (the default method)
  • "gnu" — the one used by the GNU C++ compiler (g++)
  • "lucid" — the one used by the Lucid compiler (lcc)
  • "arm" — the one specified by the C++ Annotated Reference Manual
  • "hp" — the one used by the HP compiler (aCC)
  • "edg" — the one used by the EDG compiler
  • "gnu-v3" — the one used by the GNU C++ compiler (g++) with the V3 ABI.
  • "java" — the one used by the GNU Java compiler (gcj)
  • "gnat" — the one used by the GNU Ada compiler (GNAT).
• --help — print a summary of the options to c++filt and exit. bye bestie 👋
• --version — print the version number of c++filt and exit.
• @file — 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. 🌀

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🦋 FOOTNOTES 🦋

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

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🌈 SEE ALSO 🌈

the Info entries for binutils.

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👑 COPYRIGHT 👑

Copyright (c) 1991-2026 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 License".

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and that's the whole page, babe 💅 this was binutils-2.47, dated 2026-08-11 — go demangle something iconic, you've got this 🫶✨