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clang-format C/C++ code formatter

Version 23.1 · source

clang-format, Postcard, light preview Light · Postcard 102 × 152 mm · PDF clang-format, Postcard, dark preview Dark · Postcard 102 × 152 mm · PDF clang-format, Postcard, ink saver preview Ink saver · Postcard 102 × 152 mm · PDF
clang-format, A5, light preview Light · A5 148 × 210 mm · PDF clang-format, A5, dark preview Dark · A5 148 × 210 mm · PDF clang-format, A5, ink saver preview Ink saver · A5 148 × 210 mm · PDF
clang-format, A4, light preview Light · A4 210 × 297 mm · PDF clang-format, A4, dark preview Dark · A4 210 × 297 mm · PDF clang-format, A4, ink saver preview Ink saver · A4 210 × 297 mm · PDF
clang-format, A4 landscape, light preview Light · A4 landscape 297 × 210 mm · PDF clang-format, A4 landscape, dark preview Dark · A4 landscape 297 × 210 mm · PDF clang-format, A4 landscape, ink saver preview Ink saver · A4 landscape 297 × 210 mm · PDF
clang-format, A3, light preview Light · A3 297 × 420 mm · PDF clang-format, A3, dark preview Dark · A3 297 × 420 mm · PDF clang-format, A3, ink saver preview Ink saver · A3 297 × 420 mm · PDF
clang-format, A3 landscape, light preview Light · A3 landscape 420 × 297 mm · PDF clang-format, A3 landscape, dark preview Dark · A3 landscape 420 × 297 mm · PDF clang-format, A3 landscape, ink saver preview Ink saver · A3 landscape 420 × 297 mm · PDF
clang-format, Letter, light preview Light · Letter 8.5 × 11 in · PDF clang-format, Letter, dark preview Dark · Letter 8.5 × 11 in · PDF clang-format, Letter, ink saver preview Ink saver · Letter 8.5 × 11 in · PDF
clang-format, Tabloid, light preview Light · Tabloid 11 × 17 in · PDF clang-format, Tabloid, dark preview Dark · Tabloid 11 × 17 in · PDF clang-format, Tabloid, ink saver preview Ink saver · Tabloid 11 × 17 in · PDF

Start here

clang-format -i <file>
Format a file in place
clang-format --style=file <file>
Print with project style
clang-format --dry-run -Werror <file>
Check only, fail if unformatted
clang-format --style=Google -i <file>
Use a preset style
clang-format --dump-config
Show the active settings
clang-format -style=llvm --dump-config > .clang-format
Start a config file
git clang-format
Format staged changes only
// clang-format off
Protect a region

Concepts

  1. Source file or stdin
  2. .clang-format nearest parent dir
  3. Formatted code stdout or in place

Run

clang-format <file>
Print formatted code to stdout
clang-format -i <file>...
Rewrite files in place
clang-format --style=<style> <file>
Pick a preset or file
clang-format --version
Show the version
clang-format -i src/*.cpp include/*.h
Format many files
clang-format --lines=<start>:<end> -i <file>
Format only a line range
clang-format --lines=10:20 --lines=40:50 <file>
Several ranges at once
clang-format --verbose -i <file>...
List files as they are processed
clang-format --files=<list> -i
Read file names from a list
<cmd> | clang-format --assume-filename=<name>
Format stdin as that file type
clang-format --offset=<n> --length=<n> <file>
Format a byte range
clang-format --cursor=<n> <file>
Report new cursor position

Check (CI)

clang-format --dry-run <file>
Report violations, change nothing
clang-format -n -Werror <file>
Exit non-zero if unformatted
clang-format --dry-run -Werror --ferror-limit=1 <file>
Stop at the first problem
clang-format --fail-on-incomplete-format <file>
Exit 1 if code could not be fully formatted
clang-format --output-replacements-xml <file>
Emit edits as XML
clang-format --Wno-error=unknown -n -Werror <file>
Tolerate unknown config keys
Handy when team members run different clang-format versions.
git ls-files '*.c' '*.h' | xargs clang-format -n -Werror
Check all tracked sources

Styles & config

--style=LLVM
Preset: LLVM (default)
--style=Google
Preset: Google
--style=Chromium / Mozilla / WebKit
Other browser presets
--style=Microsoft / GNU
More presets
--style=file
Use nearest .clang-format
--style=file:<path>
Use a specific config file
--style="{BasedOnStyle: Google, IndentWidth: 4}"
Inline settings
--fallback-style=<style>
Style when no config is found
--fallback-style=none
Skip formatting without a config
clang-format -style=<style> --dump-config > .clang-format
Write a full config file
clang-format --dump-config
Show config for the cwd
clang-format --dump-config --assume-filename=<f>
Show config used for a file

.clang-format keys

BasedOnStyle: Google
Start from a preset
BasedOnStyle: InheritParentConfig
Inherit parent directory's file
IndentWidth: 4
Spaces per indent level
ColumnLimit: 100
Maximum line width (0 = none)
UseTab: Never
Tabs: Never, ForIndentation, Always
BreakBeforeBraces: Allman
Brace style: Attach, Linux, Allman
PointerAlignment: Left
Align * and & left, right or middle
SortIncludes: CaseSensitive
Sort #include lines (or Never)
IncludeBlocks: Regroup
Merge, Preserve or Regroup blocks
IndentCaseLabels: true
Indent case inside switch
AccessModifierOffset: -2
Offset for public:/private:
NamespaceIndentation: None
Indent inside namespaces (None/Inner/All)
BinPackArguments: false
One argument per line when wrapping
InsertBraces: true
Add braces to bare if/for bodies
Marked experimental in the docs: can change code, so review the diff.
Language: Cpp
Limit a section to one language
Multi-language file
Part Meaning
--- Separates sections
Language: Cpp Applies to C and C++
Language: JavaScript Applies to JS/TS-like files
no Language Default for all languages

Git integration

git clang-format
Format staged changes
git clang-format <commit>
Format lines changed since a commit
git clang-format main
Format all changes on a branch
git clang-format --diff
Show the diff, apply nothing
git clang-format --staged --diff
Preview for staged changes only
git clang-format -p
Choose hunks interactively
git clang-format --extensions c,h,cpp
Limit file types
git clang-format --style=<style>
Override the style
git config clangFormat.style file
Default style for git-clang-format
git diff -U0 --no-color HEAD^ | clang-format-diff.py -p1 -i
Format only the changed lines of a diff

In code & editors

// clang-format off
Stop formatting from here
// clang-format on
Resume formatting
/* clang-format off */
Block-comment form
Alt+Shift+F
VS Code: format document
Needs the C/C++ or clang-format extension; macOS uses Option+Shift+F.
Ctrl+R Ctrl+F
Visual Studio: format selection
clang-format.py
Vim: source and map a key
clang-format-region
Emacs: bind from clang-format.el

Recipes

Start a project config
clang-format -style=Google --dump-config > .clang-format# edit IndentWidth, ColumnLimit ...clang-format -i src/*.cpp
Minimal .clang-format
# .clang-formatBasedOnStyle: GoogleIndentWidth: 4ColumnLimit: 100PointerAlignment: Left
CI format check
git ls-files '*.c' '*.cpp' '*.h' \  | xargs clang-format --dry-run -Werror
Format only what you changed
git add -pgit clang-formatgit add -ugit commit