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Programming rules for C

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Programming rules for C

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This page gives a description of part of the C programming rules verified by the IBM Rational Logiscope tool.

Presentation Rules

CodePres_1_DeclarationPerLine	Each line must contain no more than one declaration.
CodePres_2_NumberStatements	The number of statements shall not exceed 100 in a function and 1000 in a module.
CodePres_3_FileLength	A file shall not exceed 2000 lines.
CodePres_4_StatementSwitch	The number of first level statements in each clause of a switch statement shall not exceed 10.
CodePres_5_StatementSwitch	The total number of statements in each clause of a switch statement shall not exceed 25 (all levels included).
CodePres_6_CommentStatementLine	A comment must be on a line without any statement. The exception concerns a comment written on a single line after a statement.
CodePres_7_ExtensionHeader	Included files have the extension .h.
CodePres_8_EnumBoolean	Systematically define a Boolean enumerated type containing two values: true and false.
CodePres_9_ParamFunction	The number of parameters of a function is limited to 7.
CodePres_10_StatementPerLine	No more than one basic statement per line.
CodePres_11_ControlStructure	A control structure (do, while, for, if, else, switch, return, break, continue) shall start on a new line.
CodePres_12_BlankLine	Function definition/declaration and function body must be separated by a blank line.
CodePres_13_Brace	Each brace (opening and closing) must be placed alone on a line.
CodePres_14_CommentDeclaration	Each declaration (type, variable, enumeration item, structure field) is commented.
CodePres_15_PointerDeclaration	In the declaration of a pointer to a data type, the * character shall be stuck to the pointer’s identifier.
CodePres_16_SpacingRef	There shall be no blank before or after the . and -> operators.
CodePres_17_SpacingOperator	Operators ++, -, & (functionAddress), * (functionRef) shall be stuck to their operand.
CodePres_18_SpacingParameter	Do not insert a blank after the opening parenthesis or before the closing one.
CodePres_19_LineLength	A line in a source file shall not exceed 80 characters.
CodePres_25_SingleLineComment	Comments shall be one line long.
CodePres_26_CommentDefinition	All the definitions got a comment.
CodePres_28_Definitions	A module’s “.c” body file must contain the “in public” definitions of the exported functions, and the “in public” definitions of the exported variables.
CodePres_29_SpacingUnaryOperator	Unary operators ! and ~ must be stuck to their operand to avoid confusion with binary operators.
CodePres_30_Define	The #define preprocessing directives shall be grouped altogether.

Rules protecting from the dangers of the C language

Complexity_13_SimpleTest	Statements like x == y ; or x != y ; shall not be used.
ControlFlow_1_NoDeadCode	There shall be no dead code, especially after goto and return statements.
ControlFlow_4_ThenElse	The then and else parts of if statements shall not be void.
ControlFlow_8_BreakPathInSwitch	Break is mandatory for case clauses containing statements.

Règles limitant la complexité du code

Complexity_1_MultipleAssignment	Pas d'affectations en cascade
Complexity_2_NoTernaryOp	Pas d'utilisation de l'opérateur ternaire "?"
Complexity_3_NoUnary+	Pas d'utilisation de l'opérateur unaire "+"
Complexity_4_NoAssignmentOp	Pas d'utilisation des opérateurs d'affectation autres que "=" comme "*=", "/=", "+="...
Complexity_5_CallResult	Utiliser la valeur de retour des fonctions
Complexity_6_++--Operators	N'utiliser "++" et "--" que dans les cas simples.
Complexity_7_NoCast	Pas de cast.
Complexity_8_NoMultipleInit	Pas d'initialisation dans des déclarations multiples.
Complexity_9_Macro	Pas de macros avec plusieurs instructions.
Complexity_10_FieldAddressing	Pour accéder à un élément de structure pointée, utiliser la notation "Ptr->Field" au lieu de "(*Ptr).Field"
Complexity_11_NoCommaAndTernary	Ne pas utiliser les opérateurs ',' et '?'.
Complexity_12_OperatorInCondition	Une condition aved plus de 4 opérateurs logiques ne doit pas contenir des opérateurs différents.
Complexity_13_SimpleTest	Les instructions du type x == y; et x != y; sont interdites
Complexity_14_InclusionLevel	Les inclusions de fichiers sont interdites dans les fichiers header.
Complexity_15_Sizeof	L'opérande du l'opérateur "sizeof" doit être entre parenthèses.

Règles permettant d'améliorer la structuration du code.

ControlFlow_10_SwitchBetterThanIf	Utiliser un switch plutôt que des tests en cascade.
ControlFlow_11_OneBreakContinue	Un seul "break" ou "continue" autorisé dans le corps d'une boucle do, while ou for.
ControlFlow_1_NoDeadCode	Pas de code après goto", "return", "break" ou "continue".
ControlFlow_2_FunctionReturn	Un seul return autorisé par fonction.
ControlFlow_3_NoGoto	Pas de goto.
ControlFlow_4_ThenElse	Les parties "then" et "else" d'une structure "if" ne doivent pas être vides.
ControlFlow_5_NoBreakContinue	"break" et "continue" interdits dans le corps d'une boucle do, while ou for.
ControlFlow_6_DefaultInSwitch	La clause "default" est obligatoire dans les switchs.
ControlFlow_7_BreakInSwitch	Le "break" est obligatoire comme dernière instruction de chaque clause d'un switch.
ControlFlow_8_BreakPathInSwitch	Toutes les branches des clauses d'un switch doivent se terminer par un break.
ControlFlow_9_ControlStructureNesting	Pas plus de 6 structures de contrôles imbriquées.

Portability Rules

Portability_1_C++Keywords	Keywords from C++ language (class, new, friend...) shall not be used.
Portability_2_NoDollar	The ‘$’ character shall not be used in an identifier.
Portability_4_CharIdentifier	Use only letters, numbers and the underscore character in identifier names.
Portability_5_NoSignedRightShift	The right shift operator >> shall not be used on signed integer.
Portability_6_MainNaming	Only the exit function shall be used to go out from main.
Portability_7_NoRecursiveHeader	Header files shall not include themselves recursively.
Portability_9U_AbsolutePathInclude	File names in #include directives must be in the same case than the file name and shall not contain any absolute path.
Portability_12U_FilenameLength	File names shall be lower-case and shall not exceed 8 characters for the name and 3 characters for the extension.
Portability_13_NoTab	Tabulations shall not be used in source files.

Rules making maintenance easier

Resource_1_AccessArray	A pointer shall be used to run through successive elements of an array rather than an index.
Resource_2_ForCounter	Loop counters and control variables shall not be modified within the body of a for statement.
Resource_3_DeclarationInitSeparate	Declaration and initialisation of a variable shall be separate.
Resource_4_DeclarationInitCombine	Declaration and initialisation of a variable shall be done at the same time, if possible.
Resource_5_LocalDeclaration	Declaration of local variables in an instruction block shall not be used.
Resource_6_GlobalDeclaration	Global objects shall be declared in an inclusion file.
Resource_7_VariableUse	Declared variables shall be used.
Resource_8_FunctionUse	Declared functions shall be used.
Resource_9_ParameterUse	Function parameters shall be used.
Resource_10_NoGlobalParameter	A global variable shall not be used as a parameter.
Resource_11_InputParameter	A function’s input parameter shall be either a pointer to const, or passed by value.
Resource_12_NoExternBody	The keyword extern shall not be used in a.c file.
Resource_13_NoStaticInFunc	The keyword static shall not be used in the body of a function.
Resource_14_ExternHeader	Declarations of variables in an header file shall be preceded by extern.
Resource_15_NoFunctionHeader	Functions (other than macros) shall not be defined in a header file.
Resource_16_FileExtension	The header file shall have the extension .h and the body file the extension .c.
Resource_18_NoBodyInclusion	A .c file shall not be included in another .c file.
Resource_19_NoBitfield	Bitfields shall not be used.
Resource_20_NoAuto	Declaration of variables local to a function shall never be made with "auto".
Resource_21_ArrayInit	Initialization of an array shall conform to its structure.
Resource_22_PointerInit	A pointer shall always be initialized. If it points to no known variable, it shall be initialized to NULL.
Resource_23_WhileInit	The initial value of a parameter of a while loop shall be known before entering the loop.
Resource_24_ConstVolatileInit	Only const and volatile variables to a function shall be initialized when they are defined.
Resource_26_TypedefUnionStruct	A typedef shall not be used to mask structures or unions.
Resource_30_EnumInit	The initialization of enumeration fields shall not be explicit.
Resource_31_StructUnion	Using the union type shall be limited to declaring partially variable types.
Resource_32_ForSpecification	All parts of a for statement shall be filled.

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