Format C/C++ Code Using Clang-Format

Introduction

In a collaborative project, code formatting software, such as Clang-Format, have been widely used to make sure that the code written by different people have uniform style and format. I have just learned some basic usages of Clang-Format and documented them in this blog post.

Installation

1
$ sudo apt-get install clang-format

Format Configuration

In order to format our code, we need a configuration file .clang-format. This file could be generated from some pre-configured styles.

To generate .clang-format from style llvm, run the following command in the terminal.

1
$ clang-format -style=llvm -dump-config > .clang-format

Other candidate styles include google, chromium, mozilla, webkit, microsoft.

We could further modify the .clang-format file using our preferences. Below is my modified format file. More style examples could be found from Clang documentations.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
---
Language: Cpp
# BasedOnStyle: LLVM
AccessModifierOffset: -4 # -2
AlignAfterOpenBracket: Align
AlignConsecutiveAssignments: false
AlignConsecutiveDeclarations: false
AlignEscapedNewlines: Right
AlignOperands: true
AlignTrailingComments: true
AllowAllParametersOfDeclarationOnNextLine: true
AllowShortBlocksOnASingleLine: false
AllowShortCaseLabelsOnASingleLine: false
AllowShortFunctionsOnASingleLine: All
AllowShortIfStatementsOnASingleLine: false
AllowShortLoopsOnASingleLine: false
AlwaysBreakAfterDefinitionReturnType: None
AlwaysBreakAfterReturnType: None
AlwaysBreakBeforeMultilineStrings: false
AlwaysBreakTemplateDeclarations: true # false
BinPackArguments: true
BinPackParameters: true
BraceWrapping:
AfterClass: true # false
AfterControlStatement: true # false
AfterEnum: true # false
AfterFunction: true # false
AfterNamespace: true # false
AfterObjCDeclaration: true # false
AfterStruct: true # false
AfterUnion: true # false
AfterExternBlock: true # false
BeforeCatch: true # false
BeforeElse: true # false
IndentBraces: true # false
SplitEmptyFunction: true
SplitEmptyRecord: true
SplitEmptyNamespace: true
BreakBeforeBinaryOperators: None
BreakBeforeBraces: Allman # Attach
BreakBeforeInheritanceComma: false
BreakBeforeTernaryOperators: true
BreakConstructorInitializersBeforeComma: false
BreakConstructorInitializers: BeforeColon
BreakAfterJavaFieldAnnotations: false
BreakStringLiterals: true
ColumnLimit: 80
CommentPragmas: '^ IWYU pragma:'
CompactNamespaces: false
ConstructorInitializerAllOnOneLineOrOnePerLine: false
ConstructorInitializerIndentWidth: 4
ContinuationIndentWidth: 4
Cpp11BracedListStyle: true
DerivePointerAlignment: false
DisableFormat: false
ExperimentalAutoDetectBinPacking: false
FixNamespaceComments: true
ForEachMacros:
- foreach
- Q_FOREACH
- BOOST_FOREACH
IncludeBlocks: Preserve
IncludeCategories:
- Regex: '^"(llvm|llvm-c|clang|clang-c)/'
Priority: 2
- Regex: '^(<|"(gtest|gmock|isl|json)/)'
Priority: 3
- Regex: '.*'
Priority: 1
IncludeIsMainRegex: '(Test)?$'
IndentCaseLabels: true # false
IndentPPDirectives: None
IndentWidth: 4 #2
IndentWrappedFunctionNames: false
JavaScriptQuotes: Leave
JavaScriptWrapImports: true
KeepEmptyLinesAtTheStartOfBlocks: true
MacroBlockBegin: ''
MacroBlockEnd: ''
MaxEmptyLinesToKeep: 1
NamespaceIndentation: None
ObjCBlockIndentWidth: 2
ObjCSpaceAfterProperty: false
ObjCSpaceBeforeProtocolList: true
PenaltyBreakAssignment: 2
PenaltyBreakBeforeFirstCallParameter: 19
PenaltyBreakComment: 300
PenaltyBreakFirstLessLess: 120
PenaltyBreakString: 1000
PenaltyExcessCharacter: 1000000
PenaltyReturnTypeOnItsOwnLine: 60
PointerAlignment: Left # Right
ReflowComments: true
SortIncludes: true
SortUsingDeclarations: true
SpaceAfterCStyleCast: false
SpaceAfterTemplateKeyword: true
SpaceBeforeAssignmentOperators: true
SpaceBeforeParens: ControlStatements
SpaceInEmptyParentheses: false
SpacesBeforeTrailingComments: 1
SpacesInAngles: false
SpacesInContainerLiterals: true
SpacesInCStyleCastParentheses: false
SpacesInParentheses: false
SpacesInSquareBrackets: false
Standard: Cpp11
TabWidth: 8
UseTab: Never
...

Run Code Formatting

Clang-Format could format a single file or all files with the same file extension. For example, to format .cpp extension, run the following command in the terminal.

1
$ clang-format -i *.cpp

To format all .h, .c, .hpp, .cpp, .cu files together, run the following command in the terminal.

1
$ find . -regex '.*\.\(cpp\|hpp\|cu\|c\|h\)' -exec clang-format -style=file -i {} \;
Author

Lei Mao

Posted on

04-22-2019

Updated on

08-22-2020

Licensed under


Comments