最近在考虑团队代码风格的问题，无意间发现了一个代码格式化神器“clang-format”工具
在了解clang-format工具之前，我们先来了解一下什么是clang，什么是LLVM，什么是GCC，什么又是GNU
从百度百科上可以看到，GNU是一个类unix操作系统，其内容软件完全以GPL协议发布。全称GNU’s Not Unix
GCC是一套基于GNU系统开发的编译器，目前支持编译 C, C++, Objective-C,Fortran, Ada, Go, D等多种语言
其详细信息可以查看 GCC, the GNU Compiler Collection
LLVM最初由美国UIUC大学的chris Lattner博士主持开展，之后Apple雇了Chris Lattner，LLVM相当于也就成了Apple官方支持的编译器。
LLVM提供了编译器的相关支持，以C++编写而成，用于优化以任意程序语言编写的程序的编译时间、链接时间、运行时间、空闲时间。
其详情可以查看 The LLVM Compiler Infrastructure
clang是一个由Apple主导编写的，以LLVM为后端的前端C、C++、Objective-C语言编译器，他具有如下优势
其详情可以查看 Clang: a C language family frontend for LLVM
上面了解了一些基础知识点，现在开始本篇的主要内容介绍，使用clang-format工具格式化代码。本位以VSCode为例，作为讲解。
想要使用clang-format工具，我们需要一个名为“.clang-format”的配置文件，可以按照如下方法获取
vscode安装C/C++扩展，扩展程序将自动安装clang-format
在vsc用户设置里面搜索clang，可以找到一个名为“C_Cpp: Clang_format_style”的选项，查看他的介绍，我们可以把代码格式化风格设置为如下几种
如果将代码设置成file，那将从当前目录或父目录中的.clang-format文件来格式化代码
找到c/cc插件按照目录下的clang-format.exe工具，笔者的目录如下
“C:\Users\\.vscode\extensions\ms-vscode.cpptools-1.5.1\LLVM\bin”
打开命令行，输入.\clang-format.exe -style=“llvm” -dump-config > .clang-format命令，即可获取到一个名为.clang-format的文件，把此文件放到工程代码的根目录下，即可生效。
如果需要定制自己代码格式化风格，可以按照 Clang-Format Style Options文章修改.clang-format内容
笔者的.clang-format配置如下
---
Language: Cpp
# BasedOnStyle: LLVM
AccessModifierOffset: -2
AlignAfterOpenBracket: Align
AlignConsecutiveMacros: AcrossEmptyLines
AlignConsecutiveAssignments: AcrossEmptyLines
AlignConsecutiveBitFields: AcrossEmptyLines
AlignConsecutiveDeclarations: AcrossEmptyLines
AlignEscapedNewlines: Left
AlignOperands: Align
AlignTrailingComments: true
AllowAllArgumentsOnNextLine: true
AllowAllConstructorInitializersOnNextLine: true
AllowAllParametersOfDeclarationOnNextLine: true
AllowShortEnumsOnASingleLine: false
AllowShortBlocksOnASingleLine: false
AllowShortCaseLabelsOnASingleLine: false
AllowShortFunctionsOnASingleLine: false
AllowShortLambdasOnASingleLine: All
AllowShortIfStatementsOnASingleLine: false
AllowShortLoopsOnASingleLine: false
AlwaysBreakAfterDefinitionReturnType: None
AlwaysBreakAfterReturnType: None
AlwaysBreakBeforeMultilineStrings: false
AlwaysBreakTemplateDeclarations: MultiLine
AttributeMacros:
- __capability
BinPackArguments: false
BinPackParameters: false
BraceWrapping:
AfterCaseLabel: true
AfterClass: true
AfterControlStatement: true
AfterEnum: true
AfterFunction: true
AfterNamespace: true
AfterObjCDeclaration: true
AfterStruct: true
AfterUnion: true
AfterExternBlock: true
BeforeCatch: true
BeforeElse: true
BeforeLambdaBody: true
BeforeWhile: true
IndentBraces: true
SplitEmptyFunction: true
SplitEmptyRecord: true
SplitEmptyNamespace: true
BreakBeforeBinaryOperators: None
BreakBeforeConceptDeclarations: true
BreakBeforeBraces: Allman
BreakBeforeInheritanceComma: true
BreakInheritanceList: BeforeColon
BreakBeforeTernaryOperators: true
BreakConstructorInitializersBeforeComma: false
BreakConstructorInitializers: BeforeColon
BreakAfterJavaFieldAnnotations: false
BreakStringLiterals: false
ColumnLimit: 80
CommentPragmas: "^ IWYU pragma:"
CompactNamespaces: false
ConstructorInitializerAllOnOneLineOrOnePerLine: false
ConstructorInitializerIndentWidth: 4
ContinuationIndentWidth: 4
Cpp11BracedListStyle: true
DeriveLineEnding: true
DerivePointerAlignment: false
DisableFormat: false
EmptyLineBeforeAccessModifier: LogicalBlock
ExperimentalAutoDetectBinPacking: false
FixNamespaceComments: true
ForEachMacros:
- foreach
- Q_FOREACH
- BOOST_FOREACH
StatementAttributeLikeMacros:
- Q_EMIT
IncludeBlocks: Preserve
IncludeCategories:
- Regex: '^"(llvm|llvm-c|clang|clang-c)/'
Priority: 2
SortPriority: 0
CaseSensitive: false
- Regex: '^(<|"(gtest|gmock|isl|json)/)'
Priority: 3
SortPriority: 0
CaseSensitive: false
- Regex: ".*"
Priority: 1
SortPriority: 0
CaseSensitive: false
IncludeIsMainRegex: "(Test)?$"
IncludeIsMainSourceRegex: ""
IndentCaseLabels: false
IndentCaseBlocks: false
IndentGotoLabels: true
IndentPPDirectives: BeforeHash
IndentExternBlock: AfterExternBlock
IndentRequires: false
IndentWidth: 2
IndentWrappedFunctionNames: false
InsertTrailingCommas: None
JavaScriptQuotes: Leave
JavaScriptWrapImports: true
KeepEmptyLinesAtTheStartOfBlocks: false
MacroBlockBegin: ""
MacroBlockEnd: ""
MaxEmptyLinesToKeep: 1
NamespaceIndentation: None
ObjCBinPackProtocolList: Auto
ObjCBlockIndentWidth: 2
ObjCBreakBeforeNestedBlockParam: true
ObjCSpaceAfterProperty: false
ObjCSpaceBeforeProtocolList: true
PenaltyBreakAssignment: 2
PenaltyBreakBeforeFirstCallParameter: 19
PenaltyBreakComment: 300
PenaltyBreakFirstLessLess: 120
PenaltyBreakString: 1000
PenaltyBreakTemplateDeclaration: 10
PenaltyExcessCharacter: 1000000
PenaltyReturnTypeOnItsOwnLine: 60
PenaltyIndentedWhitespace: 0
PointerAlignment: Right
ReflowComments: true
SortIncludes: false
SortJavaStaticImport: Before
SortUsingDeclarations: false
SpaceAfterCStyleCast: false
SpaceAfterLogicalNot: false
SpaceAfterTemplateKeyword: true
SpaceBeforeAssignmentOperators: true
SpaceBeforeCaseColon: false
SpaceBeforeCpp11BracedList: true
SpaceBeforeCtorInitializerColon: true
SpaceBeforeInheritanceColon: true
SpaceBeforeParens: ControlStatements
SpaceAroundPointerQualifiers: Default
SpaceBeforeRangeBasedForLoopColon: true
SpaceInEmptyBlock: false
SpaceInEmptyParentheses: false
SpacesBeforeTrailingComments: 1
SpacesInAngles: false
SpacesInConditionalStatement: false
SpacesInContainerLiterals: true
SpacesInCStyleCastParentheses: false
SpacesInParentheses: false
SpacesInSquareBrackets: false
SpaceBeforeSquareBrackets: false
BitFieldColonSpacing: Both
Standard: Latest
StatementMacros:
- Q_UNUSED
- QT_REQUIRE_VERSION
TabWidth: 4
UseCRLF: false
UseTab: Never
WhitespaceSensitiveMacros:
- STRINGIZE
- PP_STRINGIZE
- BOOST_PP_STRINGIZE
- NS_SWIFT_NAME
- CF_SWIFT_NAME
---
笔者留言：
笔者正在嵌入式学习路上摸爬滚打 💪
对于一些知识点的理解难免会有出入，还请读者不吝赐教 ✋
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