C++FILT(1)

🌸 NAME 🌸

okay so this is C++FILT(1) from the GNU Development Tools, and it's literally about c++filt — the program whose whole vibe is demangle C++ and Java symbols. That's the name, bestie, slay.

✨ SYNOPSIS ✨

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

💅 DESCRIPTION 💅

okay so C++ and Java have this iconic thing called function overloading — you can write a bunch of functions with the same name as long as each one takes parameters of different types. To tell all these similarly named functions apart, C++ and Java encode them into a low-level assembler name that uniquely identifies each different version. That whole process is called mangling. The c++filt [1] program does the inverse mapping: it decodes (demangles) low-level names back into user-level names so they're actually readable.

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. obsessed.

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 example:

                    .type   _Z1fv, @function

🎀 OPTIONS 🎀

bestie, here's every single flag — no skipping, periodt. 💖

• -_, --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.
• -p, --no-params — When demangling the name of a function, do not display the types of the function's parameters.
• -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".
• -i, --no-verbose — Do not include implementation details (if any) in the demangled output.
• -s format, --format=format — c++filt can decode various methods of mangling, used by different compilers. The argument to this option selects which method it 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.

🌈 SEE ALSO 🌈

the Info entries for binutils. that's the whole see-also, iykyk 🫶

👑 COPYRIGHT 👑

Copyright (c) 1991-2018 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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okay bestie, this iconic little page is from binutils-2.30, dated 2018-01-27 — that's the C++FILT(1) footer, and we ate 💅✨