int32_ta=sum(4,3);/*OK*/int32_ta=sum(4,3);/*Wrong*/

size_ti;for(i=0;i<5;++i){/*OK*/}for(i=0;i<5;++i){/*Wrong*/}for(i=0;i<5;++i)/*Wrong*/{}

//微信公众号：嵌入式大杂烩int32_ta;a=3+4;/*OK*/for(a=0;a<5;++a)/*OK*/a=3+4;/*Wrong*/a=3+4;/*Wrong*/for(a=0;a<5;++a)/*Wrong*/

//微信公众号：嵌入式大杂烩func_name(5,4);/*OK*/func_name(4,3);/*Wrong*/

staticint32_ta;/*OK*/staticint32_tb=4;/*OK*/staticint32_ta=0;/*Wrong*/voidmy_func(void){staticint32_t*ptr;/*OK*/staticcharabc=0;/*Wrong*/}

voidmy_func(void){chara;/*OK*/charb;/*Wrong,variablewithchartypealreadyexists*/chara,b;/*OK*/}

i.自定义结构和枚举

ii.整数类型，更宽的无符号类型优先

(相关资料图)

iii.单/双浮点

intmy_func(void){/*1*/my_struct_tmy;/*Firstcustomstructures*/my_struct_ptr_t*p;/*Pointerstoo*//*2*/uint32_ta;int32_tb;uint16_tc;int16_tg;charh;/*...*//*3*/doubled;floatf;}

/*OK*/for(size_ti=0;i<10;++i)/*OK,ifyouneedcountervariablelater*/size_ti;for(i=0;i<10;++i){if(...){break;}}if(i==10){}/*Wrong*/size_ti;for(i=0;i<10;++i)...

voida(void){/*Avoidfunctioncallswhendeclaringvariable*/int32_ta,b=sum(1,2);/*Usethis*/int32_ta,b;b=sum(1,2);/*Thisisok*/uint8_ta=3,b=4;}

/*OK*/uint8_tstatus;status=0;/*Wrong*/#includeboolstatus=true;

void*ptr;/*...*//*OK,compareagainstNULL*/if(ptr==NULL||ptr!=NULL){}/*Wrong*/if(ptr||!ptr){}

int32_ta=0;...a++;/*Wrong*/++a;/*OK*/for(size_tj=0;j<10;++j){}/*OK*/

/*Whendcouldbemodified,datapointedtobydcouldnotbemodified*/voidmy_func(constvoid*d){}/*Whendanddatapointedtobydbothcouldnotbemodified*/voidmy_func(constvoid*constd){}/*Notrequired,itisadvised*/voidmy_func(constsize_tlen){}/*Whendshouldnotbemodifiedinsidefunction,onlydatapointedtobydcouldbemodified*/voidmy_func(void*constd){}

/**Tosenddata,functionshouldnotmodifymemorypointedtoby`data`variable*thus`const`keywordisimportant**Tosendgenericdata(ortowritethemtofile)*anytypemaybepassedfordata,*thususe`void*`*//*OKexample*/voidsend_data(constvoid*data,size_tlen){/*OK*//*Donotcast`void*`or`constvoid*`*/constuint8_t*d=data;/*Functionhandlespropertypeforinternalusage*/}voidsend_data(constvoid*data,intlen){/*Wrong,notnotuseint*/}

/*OK*/#includevoidmy_func(size_tsize){int32_t*arr;arr=malloc(sizeof(*arr)*n);/*OK,Allocatememory*/arr=malloc(sizeof*arr*n);/*Wrong,bracketsforsizeofoperatoraremissing*/if(arr==NULL){/*FAIL,nomemory*/}free(arr);/*Freememoryafterusage*/}/*Wrong*/voidmy_func(size_tsize){int32_tarr[size];/*Wrong,donotuseVLA*/}

size_tlength=5;/*Countervariable*/uint8_tis_ok=0;/*Boolean-treatedvariable*/if(length)/*Wrong,lengthisnottreatedasboolean*/if(length>0)/*OK,lengthistreatedascountervariablecontainingmultivalues,notonly0or1*/if(length==0)/*OK,lengthistreatedascountervariablecontainingmultivalues,notonly0or1*/if(is_ok)/*OK,variableistreatedasboolean*/if(!is_ok)/*OK,-||-*/if(is_ok==1)/*Wrong,nevercomparebooleanvariableagainst1!*/if(is_ok==0)/*Wrong,use!fornegativecheck*/

注释

//Thisiscomment(wrong)/*Thisiscomment(ok)*/

/**Thisismulti-linecomments,*writtenin2lines(ok)*//***Wrong,usedouble-asteriskonlyfordoxygendocumentation*//**Singlelinecommentwithoutspacebeforeasterisk(wrong)*//**Singlelinecommentinmulti-lineconfiguration(wrong)*//*Singlelinecomment(ok)*/

voidmy_func(void){chara,b;a=call_func_returning_char_a(a);/*Thisiscommentwith12*4spacesindentfrombeginningofline*/b=call_func_returning_char_a_but_func_name_is_very_long(a);/*Thisiscomment,alignedto4-spacesindent*/}

函数

/*OK*/voidmy_func(void);voidmyfunc(void);/*Wrong*/voidMYFunc(void);voidmyFunc();

/*OK*/constchar*my_func(void);my_struct_t*my_func(int32_ta,int32_tb);/*Wrong*/constchar*my_func(void);my_struct_t*my_func(void);

/*OK,functionnamesaligned*/voidset(int32_ta);my_type_tget(void);my_ptr_t*get_ptr(void);/*Wrong*/voidset(int32_ta);constchar*get(void);

/*OK*/int32_tfoo(void){return0;}/*OK*/staticconstchar*get_string(void){return"Helloworld!\r\n";}/*Wrong*/int32_tfoo(void){return0;}

变量

/*OK*/int32_ta;int32_tmy_var;int32_tmyvar;/*Wrong*/int32_tA;int32_tmyVar;int32_tMYVar;

voidfoo(void){int32_ta,b;/*OK*/chara;charb;/*Wrong,chartypealreadyexists*/}

voidfoo(void){int32_ta;a=bar();int32_tb;/*Wrong,thereisalreadyexecutablestatement*/}

int32_ta,b;a=foo();if(a){int32_tc,d;/*OK,canddareinif-statementscope*/c=foo();int32_te;/*Wrong,therewasalreadyexecutablestatementinsideblock*/}

/*OK*/char*a;/*Wrong*/char*a;char*a;

/*OK*/char*p,*n;

结构、枚举类型定义

在声明结构体时，它可以使用以下三种不同的选项之一:

1、当结构体仅用名称声明时，它的名称后不能包含_t后缀。

structstruct_name{char*a;charb;};

2、当只使用typedef声明结构时，它的名称后面必须包含_t后缀。

typedefstruct{char*a;charb;}struct_name_t;

3、当结构用name和typedef声明时，它不能包含_t作为基本名称，它必须在它的名称后面包含_t后缀作为typedef部分。

typedefstructstruct_name{char*a;charb;charc;}struct_name_t;

错误声明的例子及其建议的纠正：

/*aandbmustbeseparatedto2lines*//*Nameofstructurewithtypedefmustinclude_tsuffix*/typedefstruct{int32_ta,b;}a;/*Correctedversion*/typedefstruct{int32_ta;int32_tb;}a_t;/*Wrongname,itmustnotinclude_tsuffix*/structname_t{int32_ta;int32_tb;};/*Wrongparameters,mustbealluppercase*/typedefenum{MY_ENUM_TESTA,my_enum_testb,}my_enum_t;

/*OK*/a_ta={.a=4,.b=5,};/*Wrong*/a_ta={1,2};

/*Functionaccepts2parametersandreturnsuint8_t*//*Nameoftypedefhas`_fn`suffix*/typedefuint8_t(*my_func_typedef_fn)(uint8_tp1,constchar*p2);

复合语句

/*OK*/if(c){do_a();}else{do_b();}/*Wrong*/if(c)do_a();elsedo_b();/*Wrong*/if(c)do_a();elsedo_b();

/*OK*/if(a){}elseif(b){}else{}/*Wrong*/if(a){}else{}/*Wrong*/if(a){}else{}

/*OK*/do{int32_ta;a=do_a();do_b(a);}while(check());/*Wrong*/do{/*...*/}while(check());/*Wrong*/do{/*...*/}while(check());

if(a){do_a();}else{do_b();if(c){do_c();}}

if(a)do_b();elsedo_c();if(a)do_a();elsedo_b();

/*OK*/while(is_register_bit_set()){}/*Wrong*/while(is_register_bit_set());while(is_register_bit_set()){}while(is_register_bit_set()){}

/*Waitforbittobesetinembeddedhardwareunituint32_t*addr=HW_PERIPH_REGISTER_ADDR;/*Waitbit13tobeready*/while(*addr&(1<<13)){}/*OK,emptyloopcontainsnospacesinsidecurlybrackets*/while(*addr&(1<<13)){}/*Wrong*/while(*addr&(1<<13)){/*Wrong*/}while(*addr&(1<<13));/*Wrong,curlybracketsaremissing.Canleadtocompilerwarningsorunintentionalbugs*/

/*Notrecommended*/int32_ta=0;while(a<10){......++a;}/*Better*/for(size_ta=0;a<10;++a){}/*Better,ifincmaynothappenineverycycle*/for(size_ta=0;a<10;){if(...){++a;}}

分支语句

/*OK,everycasehassingleindent*//*OK,everybreakhasadditionalindent*/switch(check()){case0:do_a();break;case1:do_b();break;default:break;}/*Wrong,caseindentmissing*/switch(check()){case0:do_a();break;case1:do_b();break;default:break;}/*Wrong*/switch(check()){case0:do_a();break;/*Wrong,breakmusthaveindentasitisundercase*/case1:do_b();/*Wrong,indentundercaseismissing*/break;default:break;}

/*OK*/switch(var){case0:do_job();break;default:break;}/*Wrong,defaultismissing*/switch(var){case0:do_job();break;}

switch(a){/*OK*/case0:{int32_ta,b;charc;a=5;/*...*/break;}/*Wrong*/case1:{int32_ta;break;}/*Wrong,breakshallbeinside*/case2:{int32_ta;}break;}

宏和预处理指令

/*OK*/#defineMY_MACRO(x)((x)*(x))/*Wrong*/#definesquare(x)((x)*(x))

/*OK*/#defineMIN(x,y)((x)<(y)?(x):(y))/*Wrong*/#defineMIN(x,y)x

/*Wrong*/#defineMIN(x,y)(x)<(y)?(x):(y)#defineSUM(x,y)(x)+(y)/*ImagineresultofthisequationusingwrongSUMimplementation*/int32_tx=5*SUM(3,4);/*Expectedresultis5*7=35*/int32_tx=5*(3)+(4);/*Itisevaluatedtothis,finalresult=19whichisnotwhatweexpect*//*Correctimplementation*/#defineMIN(x,y)((x)<(y)?(x):(y))#defineSUM(x,y)((x)+(y))

typedefstruct{int32_tpx,py;}point_t;point_tp;/*Definenewpoint*//*Wrongimplementation*//*Definemacrotosetpoint*/#defineSET_POINT(p,x,y)(p)->px=(x);(p)->py=(y)/*2statements.Lastoneshouldnotimplementsemicolon*/SET_POINT(&p,3,4);/*Setpointtoposition3,4.Thisevaluatesto...*/(&p)->px=(3);(&p)->py=(4);/*...tothis.Inthisexamplethisisnotaproblem.*//*Considerthisuglycode,howeveritisvalidbyCstandard(notrecommended)*/if(a)/*Ifaistrue*/if(b)/*Ifbistrue*/SET_POINT(&p,3,4);/*Setpointtox=3,y=4*/elseSET_POINT(&p,5,6);/*Setpointtox=5,y=6*//*Evaluatestocodebelow.Doyouseetheproblem?*/if(a)if(b)(&p)->px=(3);(&p)->py=(4);else(&p)->px=(5);(&p)->py=(6);/*Orifwerewriteitalittle*/if(a)if(b)(&p)->px=(3);(&p)->py=(4);else(&p)->px=(5);(&p)->py=(6);/**Askyourselfaquestion:Towhich`if`statement`else`keywordbelongs?**Basedonfirstpartofcode,answerisstraight-forward.Toinner`if`statementwhenwecheck`b`condition*Actualanswer:Compilationerroras`else`belongsnowhere*//*Betterandcorrectimplementationofmacro*/#defineSET_POINT(p,x,y)do{(p)->px=(x);(p)->py=(y);}while(0)/*2statements.Nosemicolonafterwhileloop*//*Orevenbetter*/#defineSET_POINT(p,x,y)do{\/*Backslashindicatesstatementcontinuesinnewline*/(p)->px=(x);\(p)->py=(y);\}while(0)/*2statements.Nosemicolonafterwhileloop*//*Noworiginalcodeevaluatesto*/if(a)if(b)do{(&p)->px=(3);(&p)->py=(4);}while(0);elsedo{(&p)->px=(5);(&p)->py=(6);}while(0);/*Everypartof`if`or`else`containsonly`1`innerstatement(do-while),hencethisisvalidevaluation*//*Tomakecodeperfect,usebracketsforeveryif-ifelse-elsestatements*/if(a){/*Ifaistrue*/if(b){/*Ifbistrue*/SET_POINT(&p,3,4);/*Setpointtox=3,y=4*/}else{SET_POINT(&p,5,6);/*Setpointtox=5,y=6*/}}

/*OK*/#ifdefined(XYZ)#ifdefined(ABC)/*dowhenABCdefined*/#endif/*defined(ABC)*/#else/*defined(XYZ)*//*DowhenXYZnotdefined*/#endif/*!defined(XYZ)*//*Wrong*/#ifdefined(XYZ)#ifdefined(ABC)/*dowhenABCdefined*/#endif/*defined(ABC)*/#else/*defined(XYZ)*//*DowhenXYZnotdefined*/#endif/*!defined(XYZ)*/

文档

文档化的代码允许doxygen解析和通用的html/pdf/latex输出，因此正确地执行是非常重要的。

/***\briefHoldspointertofirstentryinlinkedlist*Beginningofthistextis5tabs(20spaces)frombeginningofline*/statictype_t*list;

/***\briefThisispointstruct*\noteThisstructureisusedtocalculateallpoint*relatedstuff*/typedefstruct{int32_tx;/*!

/***\briefSum`2`numbers*\param[in]a:Firstnumber*\param[in]b:Secondnumber*\returnSumofinputvalues*/int32_tsum(int32_ta,int32_tb){returna+b;}/***\briefSum`2`numbersandwriteittopointer*\noteThisfunctiondoesnotreturnvalue,itstoresittopointerinstead*\param[in]a:Firstnumber*\param[in]b:Secondnumber*\param[out]result:Outputvariableusedtosaveresult*/voidvoid_sum(int32_ta,int32_tb,int32_t*result){*result=a+b;}

/***\briefMyenumeration*/typedefenum{MY_ERR,/*!

/***\briefGetdatafrominputarray*\param[in]in:Inputdata*\returnPointertooutputdataonsuccess,`NULL`otherwise*/constvoid*get_data(constvoid*in){returnin;}

/***\briefGetminimalvaluebetween`x`and`y`*\param[in]x:Firstvalue*\param[in]y:Secondvalue*\returnMinimalvaluebetween`x`and`y`*\hideinitializer*/#defineMIN(x,y)((x)<(y)?(x):(y))

头/源文件

/***\filetemplate.h*\briefTemplateincludefile*//*Hereisemptyline*/

/***\filetemplate.h*\briefTemplateincludefile*//**Copyright(c)yearFirstNameLASTNAME**Permissionisherebygranted,freeofcharge,toanyperson*obtainingacopyofthissoftwareandassociateddocumentation*files(the"Software"),todealintheSoftwarewithoutrestriction,*includingwithoutlimitationtherightstouse,copy,modify,merge,*publish,distribute,sublicense,and/orsellcopiesoftheSoftware,*andtopermitpersonstowhomtheSoftwareisfurnishedtodoso,*subjecttothefollowingconditions:**Theabovecopyrightnoticeandthispermissionnoticeshallbe*includedinallcopiesorsubstantialportionsoftheSoftware.**THESOFTWAREISPROVIDED"ASIS",WITHOUTWARRANTYOFANYKIND,*EXPRESSORIMPLIED,INCLUDINGBUTNOTLIMITEDTOTHEWARRANTIES*OFMERCHANTABILITY,FITNESSFORAPARTICULARPURPOSE*ANDNONINFRINGEMENT.INNOEVENTSHALLTHEAUTHORSORCOPYRIGHT*HOLDERSBELIABLEFORANYCLAIM,DAMAGESOROTHERLIABILITY,*WHETHERINANACTIONOFCONTRACT,TORTOROTHERWISE,ARISING*FROM,OUTOFORINCONNECTIONWITHTHESOFTWAREORTHEUSEOR*OTHERDEALINGSINTHESOFTWARE.**Thisfileispartoflibrary_name.**Author:FirstNameLASTNAME*/

/*file.h...*/#ifndef...externint32_tmy_variable;/*Thisisglobalvariabledeclarationinheader*/#endif/*file.c...*/int32_tmy_variable;/*Actuallydefinedinsource*/

/*Licensecomeshere*/#ifndefTEMPLATE_HDR_H#defineTEMPLATE_HDR_H/*Includeheaders*/#ifdef__cplusplusextern"C"{#endif/*__cplusplus*//*Filecontenthere*/#ifdef__cplusplus}#endif/*__cplusplus*/#endif/*TEMPLATE_HDR_H*/

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