9 c++filt

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

The C++ and Java languages provide function overloading, which meansthat you can write many functions with the same name, providing thateach function takes parameters of different types. In order to beable to distinguish these similarly named functions C++ and Javaencode them into a low-level assembler name which uniquely identifieseach different version. This process is known as mangling. Thec++filt ¹ program does the inverse mapping: it decodes (demangles) low-levelnames 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 thelow-level name in the output, otherwise the original word is output. In this way you can pass an entire assembler source file, containingmangled names, through c++filt and see the same source filecontaining demangled names.

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

     c++filt symbol

If no symbol arguments are given, c++filt reads symbolnames from the standard input instead. All the results are printed onthe standard output. The difference between reading names from thecommand line versus reading names from the standard input is thatcommand line arguments are expected to be just mangled names and nochecking is performed to separate them from surrounding text. Thusfor 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 mangledname 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 atrailing comma. This behaviour is because when the names are readfrom the standard input it is expected that they might be part of anassembler source file where there might be extra, extraneouscharacters trailing after a mangled name. For example:

         .type   _Z1fv, @function

-_

--strip-underscores

On some systems, both the C and C++ compilers put an underscore in frontof every name. For example, the C name foo gets the low-levelname _foo. This option removes the initial underscore. Whetherc++filt removes the underscore by default is target dependent.

-j

--java

Prints demangled names using Java syntax. The default is to use C++syntax.

-n

--no-strip-underscores

Do not remove the initial underscore.

-p

--no-params

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

-t

--types

Attempt to demangle types as well as function names. This is disabledby default since mangled types are normally only used internally inthe compiler, and they can be confused with non-mangled names. For example,a function called “a” treated as a mangled type name would bedemangled to “signed char”.

-i

--no-verbose

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

-s format

--format= format

c++filt can decode various methods of mangling, used bydifferent compilers. The argument to this option selects whichmethod 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.

Warning: c++filt is a new utility, and the details of itsuser interface are subject to change in future releases. In particular,a command-line option may be required in the future to decode a namepassed as an argument on the command line; in other words,

          c++filt symbol

may in a future release become

          c++filt option
symbol

Reference Home

Corrections, suggestions, and new documentation should be posted to the Forum.

The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.