C++FILT(1)

📦
version 2.47 · 3 versions
, in arch rolling

💅 c++filt — the GNU Development Tools glow-up ✨

okay so bestie, welcome to c++filt, a certified icon of the GNU Development Tools lineup 🎀 she's here to demangle your C++ and Java symbols and honestly? she ate.

🌸 NAME 🌸

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

✨ 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...]

no cap, that's the whole vibe check right there 👑

💖 DESCRIPTION 💖

so C++ and Java both do this thing called function overloading — meaning you can literally write a bunch of functions all with the same name, as long as each one takes parameters of different types. main character energy, honestly. but to tell all these same-named functions apart, C++ and Java encode them into a low-level assembler name that uniquely identifies each different version. this whole process is called mangling 😭 (yes that's the real word, we don't make the rules).

the c++filt [1] program does the inverse mapping: it decodes (demangles) low-level names back into user-level names so that they're actually readable. obsessed. 🫶

every alphanumeric word (consisting of 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, the C++ name replaces the low-level name in the output — otherwise the original word just gets output 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, but with demangled names. slay. ✨

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

c++filt <symbol>

if you don't give her any symbol arguments, c++filt reads symbol names from the standard input instead. all the results get printed on the standard output. 💅

here's the tea though — the difference between reading names from the command line vs. reading names from 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. so 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. and why, you ask? because when the names are read from the 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 for example:

            .type   _Z1fv, @function

iykyk 😌

🎀 OPTIONS 🎀

  • -_, --strip-underscore — 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 👀
  • -n, --no-strip-underscore — do not remove the initial underscore. periodt.
  • -p, --no-params — when demangling the name of a function, don't display the types of the function's parameters. minimalist queen 💅
  • -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 be confused with non-mangled names 😭 for example, a function called "a" treated as a mangled type name would be demangled to "signed char". wild.
  • -i, --no-verbose — do not include implementation details (if any) in the demangled output. keep it cute, keep it clean ✨
  • -r, -R, --recurse-limit, --no-recurse-limit, --recursion-limit, --no-recursion-limit — enables or disables a limit on the amount of recursion performed whilst demangling strings. and bestie, this one's important: 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 prevent this 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. (yes, lowercase = off, uppercase = on, keep that straight 🧠)

  • *-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. 🫶
  • --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. 🌀

🌈 FOOTNOTES 🌈

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

🦋 SEE ALSO 🦋

the Info entries for binutils. go read 'em, bestie 📚

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". 🎀

ngl this whole page is from binutils-2.47, dated 2026-09-30 — so if you're reading this in the future, hey, hope the vibes are still immaculate 💜✨
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