CPPLINT(1)

πŸ’… CPPLINT πŸ’…

okay so bestie, quick housekeeping: this is the manual page for cpplint from section 1 (User Commands), and it's literally the glow-up your C++ code has been begging for. grab a boba, we're doing this. πŸ§‹βœ¨


πŸŽ€ NAME πŸŽ€

cpplint β€” static code checker for C++ πŸ¦‹ (yes that's the whole name section, it's short and iconic, periodt)


🌸 DESCRIPTION 🌸

okay so here's the vibe. the syntax is literally this:

cpplint.py [--verbose=#]
[--output=emacs|eclipse|vs7|junit|sed|gsed]

       [--filter=-x,+y,...]  [--counting=total|toplevel|detailed]
       [--root=subdir] [--repository=path] [--linelength=digits]
       [--headers=x,y,...]  [--recursive] [--exclude=path]
       [--extensions=hpp,cpp,...]
       [--includeorder=default|standardcfirst] [--config=filename]
       [--quiet] [--version]

       <file> [file] ...

So. It's a style checker for C/C++ source files. And yes, it's a fork of the Google style checker with minor extensions β€” glow-up inherited from a very famous parent, we love a nepo baby that actually delivers. πŸ‘‘

The style guidelines it's trying to follow are these ones right here:

https://google.github.io/styleguide/cppguide.html

Every single problem gets a confidence score from 1-5, where 5 means we are certain of the problem, and 1 means it could be a legitimate construct. So like, it's giving "trust me bestie" energy, not "I know all" energy. It will miss some errors, and it is not a substitute for a code review. πŸ’€ Fr fr. It's a helper, not your senior engineer.


πŸ™ˆ Suppressing the false positives (NOLINT lore) πŸ™ˆ

To suppress false-positive errors of certain categories, add a 'NOLINT(category[, category...])' comment to the line. NOLINT or NOLINT(*) suppresses errors of all categories on that line.

To suppress categories on the next line use NOLINTNEXTLINE instead of NOLINT.

To suppress errors in a whole block of code, drop a 'NOLINTBEGIN(category[, category...])' comment on a line at the start of the block, and to end the block add a comment with 'NOLINTEND'.

important detail alert: NOLINT blocks are inclusive, so any statements on the same line as a BEGIN or END will have the error suppression applied. iykyk.

The files passed in will be linted; at least one file must be provided. Default linted extensions are ['c', 'c++', 'cc', 'cpp', 'cu', 'cuh', 'cxx', 'h', 'h++', 'hh', 'hpp', 'hxx']. Other file types will be ignored (sorry bestie, no .txt for you). Change the extensions with the --extensions flag.


✨ Flags ✨

okay this is the main character section. here's every single one, no skips, no merges, no "you get the idea". 🌈

πŸ–₯️ OUTPUT FORMATS πŸ–₯️

  • --output=emacs|eclipse|vs7|junit|sed|gsed β€” By default, the output is formatted to ease emacs parsing. Visual Studio compatible output (vs7) may also be used. Further support exists for eclipse (eclipse), and JUnit (junit). XML parsers such as those used in Jenkins and Bamboo may also be used. The sed format outputs sed commands that should fix some of the errors. Note that this requires gnu sed. If that is installed as gsed on your system (common e.g. on macOS with homebrew) you can use the gsed output format. Sed commands are written to stdout, not stderr, so you should be able to pipe output straight to a shell to run the fixes. 🫢 slay, piping.

πŸ—£οΈ VERBOSITY & QUIET πŸ—£οΈ

  • --verbose=# β€” Specify a number 0-5 to restrict errors to certain verbosity levels. Errors with lower verbosity levels have lower confidence and are more likely to be false positives. Ate with the honesty tbh.
  • --quiet β€” Don't print anything if no errors are found. silence is golden, no notes. 🀫

πŸ” FILTERING πŸ”

  • --filter=-x,+y,... β€” Specify a comma-separated list of category-filters to apply: only error messages whose category names pass the filters will be printed. (Category names are printed with the message and look like "[whitespace/indent]".) Filters are evaluated left to right. "-FOO" means "do not print categories that start with FOO". "+FOO" means "do print categories that start with FOO".

Examples:

--filter=-whitespace,+whitespace/braces
--filter=-whitespace,-runtime/printf,+runtime/printf_format
--filter=-,+build/include_what_you_use

To see a list of all the categories used in cpplint, pass no arg: --filter=

Filters can directly be limited to files and also line numbers. The syntax is category:file:line , where line is optional. The filter limitation works for both + and - and can be combined with ordinary filters:

Examples:

--filter=-whitespace:foo.h,+whitespace/braces:foo.h
--filter=-whitespace,-runtime/printf:foo.h:14,+runtime/printf_format:foo.h
--filter=-,+build/include_what_you_use:foo.h:321
  • --counting=total|toplevel|detailed β€” The total number of errors found is always printed. If 'toplevel' is provided, then the count of errors in each of the top-level categories like 'build' and 'whitespace' will also be printed. If 'detailed' is provided, then a count is provided for each category like 'legal/copyright'. it's giving receipts. 🧾

πŸ“ PATHS & HEADER GUARDS πŸ“

  • --repository=path β€” The top level directory of the repository, used to derive the header guard CPP variable. By default, this is determined by searching for a path that contains .git, .hg, or .svn. When this flag is specified, the given path is used instead. This option allows the header guard CPP variable to remain consistent even if members of a team have different repository root directories (such as when checking out a subdirectory with SVN). In addition, users of non-mainstream version control systems can use this flag to ensure readable header guard CPP variables.

Examples:

Assuming that Alice checks out ProjectName and Bob checks out ProjectName/trunk and trunk contains src/chrome/ui/browser.h, then with no --repository flag, the header guard CPP variable will be:

Alice => TRUNK_SRC_CHROME_BROWSER_UI_BROWSER_H_
Bob   => SRC_CHROME_BROWSER_UI_BROWSER_H_

If Alice uses the --repository=trunk flag and Bob omits the flag or uses --repository=. then the header guard CPP variable will be:

Alice => SRC_CHROME_BROWSER_UI_BROWSER_H_
Bob   => SRC_CHROME_BROWSER_UI_BROWSER_H_

team consistency unlocked, bestie. ✨

  • --root=subdir β€” The root directory used for deriving header guard CPP variable. This directory is relative to the top level directory of the repository which by default is determined by searching for a directory that contains .git, .hg, or .svn but can also be controlled with the --repository flag. If the specified directory does not exist, this flag is ignored.

Examples:

Assuming that src is the top level directory of the repository (and cwd=top/src), the header guard CPP variables for src/chrome/browser/ui/browser.h are:

No flag            => CHROME_BROWSER_UI_BROWSER_H_
--root=chrome      => BROWSER_UI_BROWSER_H_
--root=chrome/browser => UI_BROWSER_H_
--root=..          => SRC_CHROME_BROWSER_UI_BROWSER_H_
  • --linelength=digits β€” This is the allowed line length for the project. The default value is 80 characters. (eighty. iconic number. respect it.) πŸ“

Examples:

--linelength=120
  • --recursive β€” Search for files to lint recursively. Each directory given in the list of files to be linted is replaced by all files that descend from that directory. Files with extensions not in the valid extensions list are excluded. it goes deep. πŸ•³οΈ
  • --exclude=path β€” Exclude the given path from the list of files to be linted. Relative paths are evaluated relative to the current directory and shell globbing is performed. This flag can be provided multiple times to exclude multiple files.

Examples:

--exclude=one.cc
--exclude=src/*.cc
--exclude=src/*.cc --exclude=test/*.cc
  • --extensions=extension,extension,... β€” The allowed file extensions that cpplint will check.

Examples:

--extensions=c,c++,cc,cpp,cu,cuh,cxx,h,h++,hh,hpp,hxx

🧠 THE FANCY ONES 🧠

  • --includeorder=default|standardcfirst β€” For the build/include_order rule, the default is to blindly assume angle bracket includes with file extension are c-system-headers (default), even knowing this will have false classifications. The default is established at google. standardcfirst means to instead use an allow-list of known c headers and treat all others as separate group of "other system headers". The C headers included are those of the C-standard lib and closely related ones.
  • --config=filename β€” Search for config files with the specified name instead of CPPLINT.cfg. (yes you can rename your config file. custom era. πŸŽ€)
  • --headers=x,y,... β€” The header extensions that cpplint will treat as .h in checks. Values are automatically added to the --extensions list.

(by default, only files with extensions ['cuh', 'h', 'h++', 'hh', 'hpp', 'hxx'] will be assumed to be headers)

Examples:

--headers=cuh,h,h++,hh,hpp,hxx
--headers=hpp,hxx
--headers=hpp

βš™οΈ CPPLINT.cfg β€” the per-directory config era βš™οΈ

cpplint.py supports per-directory configurations specified in CPPLINT.cfg files. A CPPLINT.cfg file can contain a number of key=value pairs. Currently the following options are supported:

set noparent
filter=+filter1,-filter2,...
exclude_files=regex
linelength=80
root=subdir
headers=x,y,...
  • "set noparent" option prevents cpplint from traversing directory tree upwards looking for more .cfg files in parent directories. This option is usually placed in the top-level project directory.
  • The "filter" option is similar in function to --filter flag. It specifies message filters in addition to the |_DEFAULT_FILTERS| and those specified through --filter command-line flag.
  • "exclude_files" allows to specify a regular expression to be matched against a file name. If the expression matches, the file is skipped and not run through the linter. byeee πŸ‘‹
  • "linelength" allows to specify the allowed line length for the project.
  • The "root" option is similar in function to the --root flag (see example above). Paths are relative to the directory of the CPPLINT.cfg.
  • The "headers" option is similar in function to the --headers flag (see example above).

CPPLINT.cfg has an effect on files in the same directory and all sub-directories, unless overridden by a nested configuration file. it's giving ancestral rules that trickle down the tree. 🌳

Example file:

filter=-build/include_order,+build/include_alpha
exclude_files=.*\.cc

The above example disables build/include_order warning and enables build/include_alpha as well as excludes all .cc from being processed by linter, in the current directory (where the .cfg file is located) and all sub-directories. look at her go. πŸ’…


🫢 and that's the whole page bestie. keep every detail, break zero rules, lint responsibly, and remember: not a substitute for a code review. no cap.

this page is cpplint version 2.0.2, dated July 2026 β€” and honestly? she ate. mwah. πŸ’–βœ¨πŸŽ€πŸ¦‹πŸŒΈπŸ‘‘πŸŒˆβ­πŸ’œ

πŸ“¦ where this page comes from