嵌入式C編碼規(guī)范,收藏備用!
最重要的一條規(guī)則
本文引用地址:http://www.ex-cimer.com/article/202408/462049.htm編寫代碼時(shí)最重要的一條規(guī)則是:檢查周圍的代碼并嘗試模仿它。
作為維護(hù)人員,如果收到的補(bǔ)丁明顯與周圍代碼的編碼風(fēng)格不同,這是令人沮喪的。這是不尊重人的,就像某人穿著泥濘的鞋子走進(jìn)一間一塵不染的房子。
因此,無論本文推薦的是什么,如果已經(jīng)編寫了代碼并且您正在對(duì)其進(jìn)行修補(bǔ),請(qǐng)保持其當(dāng)前的樣式一致,即使它不是您最喜歡的樣式。
一般規(guī)則
這里列出了最明顯和最重要的一般規(guī)則。在你繼續(xù)閱讀其他章節(jié)之前,請(qǐng)仔細(xì)檢查它們。
· 使用C99標(biāo)準(zhǔn)
· 不使用制表符,而是使用空格
· 每個(gè)縮進(jìn)級(jí)別使用4個(gè)空格
· 在關(guān)鍵字和左括號(hào)之間使用一個(gè)空格
· 在函數(shù)名和左括號(hào)之間不要使用空格
int32_t a = sum(4, 3); /* OK */
int32_t a = sum (4, 3); /* Wrong */
· 不要在變量/函數(shù)/宏/類型中使用__或_前綴。這是為C語言本身保留的
· 對(duì)于嚴(yán)格的模塊私有函數(shù),使用prv_ name前綴
· 對(duì)于包含下劃線_ char的變量/函數(shù)/宏/類型,只能使用小寫字母
· 左花括號(hào)總是與關(guān)鍵字(for, while, do, switch, if,…)在同一行
size_t i;
for (i = 0; i < 5; ++i) { /* OK */
}
for (i = 0; i < 5; ++i){ /* Wrong */
}
for (i = 0; i < 5; ++i) /* Wrong */
{
}
· 在比較操作符和賦值操作符之前和之后使用單個(gè)空格
// 微信公眾號(hào):嵌入式大雜燴
int32_t a;
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 */
· 每個(gè)逗號(hào)后用單空格
// 微信公眾號(hào):嵌入式大雜燴
func_name(5, 4); /* OK */
func_name(4,3); /* Wrong */
· 不要初始化靜態(tài)和全局變量為0(或NULL),讓編譯器為您做
static int32_t a; /* OK */
static int32_t b = 4; /* OK */
static int32_t a = 0; /* Wrong */
void
my_func(void) {
static int32_t* ptr;/* OK */
static char abc = 0;/* Wrong */
}
· 在同一行中聲明所有相同類型的局部變量
void
my_func(void) {
char a; /* OK */
char b; /* Wrong, variable with char type already exists */
char a, b; /* OK */
}
· 按順序聲明局部變量
i. 自定義結(jié)構(gòu)和枚舉
ii. 整數(shù)類型,更寬的無符號(hào)類型優(yōu)先
iii. 單/雙浮點(diǎn)
int
my_func(void) {
/* 1 */
my_struct_t my; /* First custom structures */
my_struct_ptr_t* p; /* Pointers too */
/* 2 */
uint32_t a;
int32_t b;
uint16_t c;
int16_t g;
char h;
/* ... */
/* 3 */
double d;
float f;
}
· 總是在塊的開頭聲明局部變量,在第一個(gè)可執(zhí)行語句之前
· 在for循環(huán)中聲明計(jì)數(shù)器變量
/* OK */
for (size_t i = 0; i < 10; ++i)
/* OK, if you need counter variable later */
size_t i;
for (i = 0; i < 10; ++i) {
if (...) {
break;
}
}
if (i == 10) {
}
/* Wrong */
size_t i;
for (i = 0; i < 10; ++i) ...
· 避免在聲明中使用函數(shù)調(diào)用來賦值變量,除了單個(gè)變量
void
a(void) {
/* Avoid function calls when declaring variable */
int32_t a, b = sum(1, 2);
/* Use this */
int32_t a, b;
b = sum(1, 2);
/* This is ok */
uint8_t a = 3, b = 4;
}
· 除了char、float或double之外,始終使用stdint.h標(biāo)準(zhǔn)庫中聲明的類型。例如,8位的uint8_t等
· 不要使用stdbool.h庫。分別使用1或0表示真或假
/* OK */
uint8_t status;
status = 0;
/* Wrong */
#include <stdbool.h>
bool status = true;
· 永遠(yuǎn)不要與真實(shí)相比較。例如,使用 if(check_func()){…} 替換 if (check_func() == 1)
· 總是將指針與空值進(jìn)行比較
void* ptr;
/* ... */
/* OK, compare against NULL */
if (ptr == NULL || ptr != NULL) {
}
/* Wrong */
if (ptr || !ptr) {
}
· 總是使用前增量(和遞減),而不是后增量(和遞減)
int32_t a = 0;
...
a++; /* Wrong */
++a; /* OK */
for (size_t j = 0; j < 10; ++j) {} /* OK */
· 總是使用size_t作為長度或大小變量
· 如果函數(shù)不應(yīng)該修改指針?biāo)赶虻膬?nèi)存,則總是使用const作為指針
· 如果不應(yīng)該修改函數(shù)的形參或變量,則總是使用const
/* When d could be modified, data pointed to by d could not be modified */
void
my_func(const void* d) {
}
/* When d and data pointed to by d both could not be modified */
void
my_func(const void* const d) {
}
/* Not required, it is advised */
void
my_func(const size_t len) {
}
/* When d should not be modified inside function, only data pointed to by d could be modified */
void
my_func(void* const d) {
}
· 當(dāng)函數(shù)可以接受任何類型的指針時(shí),總是使用void *,不要使用uint8_t *。函數(shù)在實(shí)現(xiàn)時(shí)必須注意正確的類型轉(zhuǎn)換
/*
* To send data, function should not modify memory pointed to by `data` variable
* thus `const` keyword is important
*
* To send generic data (or to write them to file)
* any type may be passed for data,
* thus use `void *`
*/
/* OK example */
void
send_data(const void* data, size_t len) { /* OK */
/* Do not cast `void *` or `const void *` */
const uint8_t* d = data;/* Function handles proper type for internal usage */
}
void
send_data(const void* data, int len) { /* Wrong, not not use int */
}
· 總是使用括號(hào)和sizeof操作符
· 不要使用變長數(shù)組。使用動(dòng)態(tài)內(nèi)存分配代替標(biāo)準(zhǔn)C malloc和自由函數(shù),或者如果庫/項(xiàng)目提供了自定義內(nèi)存分配,使用它的實(shí)現(xiàn)
看看LwMEM,一個(gè)自定義內(nèi)存管理庫。
/* OK */
#include <stdlib.h>
void
my_func(size_t size) {
int32_t* arr;
arr = malloc(sizeof(*arr) * n); /* OK, Allocate memory */
arr = malloc(sizeof *arr * n); /* Wrong, brackets for sizeof operator are missing */
if (arr == NULL) {
/* FAIL, no memory */
}
free(arr); /* Free memory after usage */
}
/* Wrong */
void
my_func(size_t size) {
int32_t arr[size]; /* Wrong, do not use VLA */
}
· 總是將variable與0進(jìn)行比較,除非它被視為布爾類型
· 永遠(yuǎn)不要將布爾處理的變量與0或1進(jìn)行比較。用NOT(!)代替
size_t length = 5; /* Counter variable */
uint8_t is_ok = 0; /* Boolean-treated variable */
if (length) /* Wrong, length is not treated as boolean */
if (length > 0) /* OK, length is treated as counter variable containing multi values, not only 0 or 1 */
if (length == 0) /* OK, length is treated as counter variable containing multi values, not only 0 or 1 */
if (is_ok) /* OK, variable is treated as boolean */
if (!is_ok) /* OK, -||- */
if (is_ok == 1) /* Wrong, never compare boolean variable against 1! */
if (is_ok == 0) /* Wrong, use ! for negative check */
· 對(duì)于注釋,總是使用/* comment */,即使是單行注釋
· 在頭文件中總是包含帶有extern關(guān)鍵字的c++檢查
· 每個(gè)函數(shù)都必須包含doxygen-enabled注釋,即使函數(shù)是靜態(tài)的
· 使用英文名稱/文本的函數(shù),變量,注釋
· 變量使用小寫字母
· 如果變量包含多個(gè)名稱,請(qǐng)使用下劃線。force_redraw。不要使用forceRedraw
· 對(duì)于C標(biāo)準(zhǔn)庫的包含文件,請(qǐng)始終使用<和>。例如,# include < stdlib.h >
· 對(duì)于自定義庫,請(qǐng)始終使用""。例如,# include“my_library.h”
· 當(dāng)轉(zhuǎn)換為指針類型時(shí),總是將星號(hào)與類型對(duì)齊,例如。uint8_t* t = (uint8_t*)var_width_diff_type
· 始終尊重項(xiàng)目或庫中已經(jīng)使用的代碼風(fēng)格
注釋
· 不允許以//開頭的注釋??偸鞘褂?* comment */,即使是單行注釋
//This is comment (wrong)
/* This is comment (ok) */
· 對(duì)于多行注釋,每行使用空格+星號(hào)
/*
* This is multi-line comments,
* written in 2 lines (ok)
*/
/**
* Wrong, use double-asterisk only for doxygen documentation
*/
/*
* Single line comment without space before asterisk (wrong)
*/
/*
* Single line comment in multi-line configuration (wrong)
*/
/* Single line comment (ok) */
· 注釋時(shí)使用12個(gè)縮進(jìn)(12 * 4個(gè)空格)偏移量。如果語句大于12個(gè)縮進(jìn),將注釋4-空格對(duì)齊(下面的例子)到下一個(gè)可用縮進(jìn)
void
my_func(void) {
char a, b;
a = call_func_returning_char_a(a); /* This is comment with 12*4 spaces indent from beginning of line */
b = call_func_returning_char_a_but_func_name_is_very_long(a); /* This is comment, aligned to 4-spaces indent */
}
函數(shù)
· 每個(gè)可以從模塊外部訪問的函數(shù)都必須包含函數(shù)原型(或聲明)
· 函數(shù)名必須小寫,可以用下劃線_分隔
/* OK */
void my_func(void);
void myfunc(void);
/* Wrong */
void MYFunc(void);
void myFunc();
· 當(dāng)函數(shù)返回指針時(shí),將星號(hào)對(duì)齊到返回類型
/* OK */
const char* my_func(void);
my_struct_t* my_func(int32_t a, int32_t b);
/* Wrong */
const char *my_func(void);
my_struct_t * my_func(void);
· 對(duì)齊所有的功能原型(使用相同/相似的功能)以提高可讀性
/* OK, function names aligned */
void set(int32_t a);
my_type_t get(void);
my_ptr_t* get_ptr(void);
/* Wrong */
void set(int32_t a);
const char * get(void);
· 函數(shù)實(shí)現(xiàn)必須在單獨(dú)的行中包含返回類型和可選的其他關(guān)鍵字
/* OK */
int32_t
foo(void) {
return 0;
}
/* OK */
static const char*
get_string(void) {
return "Hello world!rn";
}
/* Wrong */
int32_t foo(void) {
return 0;
}
變量
· 使變量名全部小寫,下劃線_字符可選
/* OK */
int32_t a;
int32_t my_var;
int32_t myvar;
/* Wrong */
int32_t A;
int32_t myVar;
int32_t MYVar;
· 按類型將局部變量分組在一起
void
foo(void) {
int32_t a, b; /* OK */
char a;
char b; /* Wrong, char type already exists */
}
· 不要在第一個(gè)可執(zhí)行語句之后聲明變量
void
foo(void) {
int32_t a;
a = bar();
int32_t b; /* Wrong, there is already executable statement */
}
· 你可以在下一個(gè)縮進(jìn)級(jí)別中聲明新的變量
int32_t a, b;
a = foo();
if (a) {
int32_t c, d; /* OK, c and d are in if-statement scope */
c = foo();
int32_t e; /* Wrong, there was already executable statement inside block */
}
· 用星號(hào)聲明指針變量與類型對(duì)齊
/* OK */
char* a;
/* Wrong */
char *a;
char * a;
· 當(dāng)聲明多個(gè)指針變量時(shí),可以使用星號(hào)對(duì)變量名進(jìn)行聲明
/* OK */
char *p, *n;
結(jié)構(gòu)、枚舉類型定義
· 結(jié)構(gòu)名或枚舉名必須小寫,單詞之間有下劃線_字符
· 結(jié)構(gòu)或枚舉可以包含typedef關(guān)鍵字
· 所有結(jié)構(gòu)成員都必須小寫
· 所有枚舉成員必須是大寫的
· 結(jié)構(gòu)/枚舉必須遵循doxygen文檔語法
在聲明結(jié)構(gòu)體時(shí),它可以使用以下三種不同的選項(xiàng)之一:
1、當(dāng)結(jié)構(gòu)體僅用名稱聲明時(shí),它的名稱后不能包含_t后綴。
struct struct_name {
char* a;
char b;
};
2、當(dāng)只使用typedef聲明結(jié)構(gòu)時(shí),它的名稱后面必須包含_t后綴。
typedef struct {
char* a;
char b;
} struct_name_t;
3、當(dāng)結(jié)構(gòu)用name和typedef聲明時(shí),它不能包含_t作為基本名稱,它必須在它的名稱后面包含_t后綴作為typedef部分。
typedef struct struct_name {
char* a;
char b;
char c;
} struct_name_t;
錯(cuò)誤聲明的例子及其建議的糾正:
/* a and b must be separated to 2 lines */
/* Name of structure with typedef must include _t suffix */
typedef struct {
int32_t a, b;
} a;
/* Corrected version */
typedef struct {
int32_t a;
int32_t b;
} a_t;
/* Wrong name, it must not include _t suffix */
struct name_t {
int32_t a;
int32_t b;
};
/* Wrong parameters, must be all uppercase */
typedef enum {
MY_ENUM_TESTA,
my_enum_testb,
} my_enum_t;
· 在聲明時(shí)初始化結(jié)構(gòu)時(shí),使用C99初始化風(fēng)格
/* OK */
a_t a = {
.a = 4,
.b = 5,
};
/* Wrong */
a_t a = {1, 2};
· 當(dāng)為函數(shù)句柄引入new typedef時(shí),使用_fn后綴
/* Function accepts 2 parameters and returns uint8_t */
/* Name of typedef has `_fn` suffix */
typedef uint8_t (*my_func_typedef_fn)(uint8_t p1, const char* p2);
復(fù)合語句
· 每個(gè)復(fù)合語句必須包括左花括號(hào)和右花括號(hào),即使它只包含1個(gè)嵌套語句
· 每個(gè)復(fù)合語句必須包含單個(gè)縮進(jìn);嵌套語句時(shí),每個(gè)嵌套包含1個(gè)縮進(jìn)大小
/* OK */
if (c) {
do_a();
} else {
do_b();
}
/* Wrong */
if (c)
do_a();
else
do_b();
/* Wrong */
if (c) do_a();
else do_b();
· 在if或if-else-if語句的情況下,else必須與第一條語句的右括號(hào)在同一行
/* OK */
if (a) {
} else if (b) {
} else {
}
/* Wrong */
if (a) {
}
else {
}
/* Wrong */
if (a) {
}
else
{
}
· 在do-while語句的情況下,while部分必須與do部分的右括號(hào)在同一行
/* OK */
do {
int32_t a;
a = do_a();
do_b(a);
} while (check());
/* Wrong */
do
{
/* ... */
} while (check());
/* Wrong */
do {
/* ... */
}
while (check());
· 每一個(gè)開括號(hào)都需要縮進(jìn)
if (a) {
do_a();
} else {
do_b();
if (c) {
do_c();
}
}
· 不要做沒有花括號(hào)的復(fù)合語句,即使是單個(gè)語句。下面的例子展示了一些不好的做法
if (a) do_b();
else do_c();
if (a) do_a(); else do_b();
· 空while循環(huán)、do-while循環(huán)或for循環(huán)必須包含花括號(hào)
/* OK */
while (is_register_bit_set()) {}
/* Wrong */
while (is_register_bit_set());
while (is_register_bit_set()) { }
while (is_register_bit_set()) {
}
· 如果while(或for、do-while等)為空(嵌入式編程中也可能是這種情況),請(qǐng)使用空的單行括號(hào)
/* Wait for bit to be set in embedded hardware unit
uint32_t* addr = HW_PERIPH_REGISTER_ADDR;
/* Wait bit 13 to be ready */
while (*addr & (1 << 13)) {} /* OK, empty loop contains no spaces inside curly brackets */
while (*addr & (1 << 13)) { } /* Wrong */
while (*addr & (1 << 13)) { /* Wrong */
}
while (*addr & (1 << 13)); /* Wrong, curly brackets are missing. Can lead to compiler warnings or unintentional bugs */
· 盡量避免在循環(huán)塊內(nèi)遞增變量,參見示例
/* Not recommended */
int32_t a = 0;
while (a < 10) {
.
..
...
++a;
}
/* Better */
for (size_t a = 0; a < 10; ++a) {
}
/* Better, if inc may not happen in every cycle */
for (size_t a = 0; a < 10; ) {
if (...) {
++a;
}
}
分支語句
· 為每個(gè)case語句添加單個(gè)縮進(jìn)
· 使用額外的單縮進(jìn)break語句在每個(gè)case或default
/* OK, every case has single indent */
/* OK, every break has additional indent */
switch (check()) {
case 0:
do_a();
break;
case 1:
do_b();
break;
default:
break;
}
/* Wrong, case indent missing */
switch (check()) {
case 0:
do_a();
break;
case 1:
do_b();
break;
default:
break;
}
/* Wrong */
switch (check()) {
case 0:
do_a();
break; /* Wrong, break must have indent as it is under case */
case 1:
do_b(); /* Wrong, indent under case is missing */
break;
default:
break;
}
· 總是包含default語句
/* OK */
switch (var) {
case 0:
do_job();
break;
default: break;
}
/* Wrong, default is missing */
switch (var) {
case 0:
do_job();
break;
}
· 如果需要局部變量,則使用花括號(hào)并在里面放入break語句。將左花括號(hào)放在case語句的同一行
switch (a) {
/* OK */
case 0: {
int32_t a, b;
char c;
a = 5;
/* ... */
break;
}
/* Wrong */
case 1:
{
int32_t a;
break;
}
/* Wrong, break shall be inside */
case 2: {
int32_t a;
}
break;
}
宏和預(yù)處理指令
· 總是使用宏而不是文字常量,特別是對(duì)于數(shù)字
· 所有的宏必須是全大寫的,并帶有下劃線_字符(可選),除非它們被明確標(biāo)記為function,將來可能會(huì)被常規(guī)函數(shù)語法替換
/* OK */
#define MY_MACRO(x) ((x) * (x))
/* Wrong */
#define square(x) ((x) * (x))
· 總是用圓括號(hào)保護(hù)輸入?yún)?shù)
/* OK */
#define MIN(x, y) ((x) < (y) ? (x) : (y))
/* Wrong */
#define MIN(x, y) x < y ? x : y
· 總是用括號(hào)保護(hù)最終的宏計(jì)算
/* Wrong */
#define MIN(x, y) (x) < (y) ? (x) : (y)
#define SUM(x, y) (x) + (y)
/* Imagine result of this equation using wrong SUM implementation */
int32_t x = 5 * SUM(3, 4); /* Expected result is 5 * 7 = 35 */
int32_t x = 5 * (3) + (4); /* It is evaluated to this, final result = 19 which is not what we expect */
/* Correct implementation */
#define MIN(x, y) ((x) < (y) ? (x) : (y))
#define SUM(x, y) ((x) + (y))
· 當(dāng)宏使用多個(gè)語句時(shí),使用do-while(0)語句保護(hù)它
typedef struct {
int32_t px, py;
} point_t;
point_t p; /* Define new point */
/* Wrong implementation */
/* Define macro to set point */
#define SET_POINT(p, x, y) (p)->px = (x); (p)->py = (y) /* 2 statements. Last one should not implement semicolon */
SET_POINT(&p, 3, 4); /* Set point to position 3, 4. This evaluates to... */
(&p)->px = (3); (&p)->py = (4); /* ... to this. In this example this is not a problem. */
/* Consider this ugly code, however it is valid by C standard (not recommended) */
if (a) /* If a is true */
if (b) /* If b is true */
SET_POINT(&p, 3, 4);/* Set point to x = 3, y = 4 */
else
SET_POINT(&p, 5, 6);/* Set point to x = 5, y = 6 */
/* Evaluates to code below. Do you see the problem? */
if (a)
if (b)
(&p)->px = (3); (&p)->py = (4);
else
(&p)->px = (5); (&p)->py = (6);
/* Or if we rewrite it a little */
if (a)
if (b)
(&p)->px = (3);
(&p)->py = (4);
else
(&p)->px = (5);
(&p)->py = (6);
/*
* Ask yourself a question: To which `if` statement `else` keyword belongs?
*
* Based on first part of code, answer is straight-forward. To inner `if` statement when we check `b` condition
* Actual answer: Compilation error as `else` belongs nowhere
*/
/* Better and correct implementation of macro */
#define SET_POINT(p, x, y) do { (p)->px = (x); (p)->py = (y); } while (0) /* 2 statements. No semicolon after while loop */
/* Or even better */
#define SET_POINT(p, x, y) do { /* Backslash indicates statement continues in new line */
(p)->px = (x);
(p)->py = (y);
} while (0) /* 2 statements. No semicolon after while loop */
/* Now original code evaluates to */
if (a)
if (b)
do { (&p)->px = (3); (&p)->py = (4); } while (0);
else
do { (&p)->px = (5); (&p)->py = (6); } while (0);
/* Every part of `if` or `else` contains only `1` inner statement (do-while), hence this is valid evaluation */
/* To make code perfect, use brackets for every if-ifelse-else statements */
if (a) { /* If a is true */
if (b) { /* If b is true */
SET_POINT(&p, 3, 4);/* Set point to x = 3, y = 4 */
} else {
SET_POINT(&p, 5, 6);/* Set point to x = 5, y = 6 */
}
}
· 不縮進(jìn)子語句內(nèi)#if語句
/* OK */
#if defined(XYZ)
#if defined(ABC)
/* do when ABC defined */
#endif /* defined(ABC) */
#else /* defined(XYZ) */
/* Do when XYZ not defined */
#endif /* !defined(XYZ) */
/* Wrong */
#if defined(XYZ)
#if defined(ABC)
/* do when ABC defined */
#endif /* defined(ABC) */
#else /* defined(XYZ) */
/* Do when XYZ not defined */
#endif /* !defined(XYZ) */
文檔
文檔化的代碼允許doxygen解析和通用的html/pdf/latex輸出,因此正確地執(zhí)行是非常重要的。
· 對(duì)變量、函數(shù)和結(jié)構(gòu)/枚舉使用doxygen支持的文檔樣式
· 經(jīng)常使用作為doxygen,不要使用@
· 始終使用5x4空格(5個(gè)制表符)作為文本行開始的偏移量
/**
* brief Holds pointer to first entry in linked list
* Beginning of this text is 5 tabs (20 spaces) from beginning of line
*/
static
type_t* list;
· 每個(gè)結(jié)構(gòu)/枚舉成員都必須包含文檔
· 注釋的開頭使用12x4空格偏移量
/**
* brief This is point struct
* note This structure is used to calculate all point
* related stuff
*/
typedef struct {
int32_t x; /*!< Point X coordinate */
int32_t y; /*!< Point Y coordinate */
int32_t size; /*!< Point size.
Since comment is very big,
you may go to next line */
} point_t;
/**
* brief Point color enumeration
*/
typedef enum {
COLOR_RED, /*!< Red color. This comment has 12x4
spaces offset from beginning of line */
COLOR_GREEN, /*!< Green color */
COLOR_BLUE, /*!< Blue color */
} point_color_t;
· 函數(shù)的文檔必須在函數(shù)實(shí)現(xiàn)中編寫(通常是源文件)
· 函數(shù)必須包括簡(jiǎn)要和所有參數(shù)文檔
· 如果每個(gè)參數(shù)分別為in或out輸入和輸出,則必須注意
· 如果函數(shù)返回某個(gè)值,則必須包含返回形參。這不適用于void函數(shù)
· 函數(shù)可以包含其他doxygen關(guān)鍵字,如note或warning
· 在參數(shù)名和描述之間使用冒號(hào):
/**
* brief Sum `2` numbers
* param[in] a: First number
* param[in] b: Second number
* return Sum of input values
*/
int32_t
sum(int32_t a, int32_t b) {
return a + b;
}
/**
* brief Sum `2` numbers and write it to pointer
* note This function does not return value, it stores it to pointer instead
* param[in] a: First number
* param[in] b: Second number
* param[out] result: Output variable used to save result
*/
void
void_sum(int32_t a, int32_t b, int32_t* result) {
*result = a + b;
}
· 如果函數(shù)返回枚舉的成員,則使用ref關(guān)鍵字指定哪個(gè)成員
/**
* brief My enumeration
*/
typedef enum {
MY_ERR, /*!< Error value */
MY_OK /*!< OK value */
} my_enum_t;
/**
* brief Check some value
* return ref MY_OK on success, member of ref my_enum_t otherwise
*/
my_enum_t
check_value(void) {
return MY_OK;
}
對(duì)常量或數(shù)字使用符號(hào)(' NULL ' => NULL)
/**
* brief Get data from input array
* param[in] in: Input data
* return Pointer to output data on success, `NULL` otherwise
*/
const void *
get_data(const void* in) {
return in;
}
· 宏的文檔必須包括hideinitializer doxygen命令
/**
* brief Get minimal value between `x` and `y`
* param[in] x: First value
* param[in] y: Second value
* return Minimal value between `x` and `y`
* hideinitializer
*/
#define MIN(x, y) ((x) < (y) ? (x) : (y))
頭/源文件
· 在文件末尾留下一個(gè)空行
· 每個(gè)文件都必須包括文件的doxygen注釋和后跟空行的簡(jiǎn)要描述(使用doxygen時(shí))
/**
* file template.h
* brief Template include file
*/
/* Here is empty line */
· 每個(gè)文件(頭文件或源文件)必須包含許可證(開始注釋包括單個(gè)星號(hào),因?yàn)閐oxygen必須忽略這個(gè))
· 使用與項(xiàng)目/庫已經(jīng)使用的相同的許可證
/**
* file template.h
* brief Template include file
*/
/*
* Copyright (c) year FirstName LASTNAME
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* This file is part of library_name.
*
* Author: FirstName LASTNAME <optional_email@example.com>
*/
· 頭文件必須包含保護(hù)符#ifndef
· 頭文件必須包含c++檢查
· 在c++檢查之外包含外部頭文件
· 首先用STL C文件包含外部頭文件,然后是應(yīng)用程序自定義文件
· 頭文件必須包含其他所有頭文件,以便正確編譯,但不能包含更多頭文件(如果需要,.c應(yīng)該包含其余的頭文件)
· 頭文件必須只公開模塊公共變量/類型/函數(shù)
· 在頭文件中使用extern作為全局模塊變量,稍后在源文件中定義它們
/* file.h ... */
#ifndef ...
extern int32_t my_variable; /* This is global variable declaration in header */
#endif
/* file.c ... */
int32_t my_variable; /* Actually defined in source */
· 不要把.c文件包含在另一個(gè).c文件中
· .c文件應(yīng)該首先包含相應(yīng)的.h文件,然后是其他文件,除非另有明確的必要
· 在頭文件中不包含模塊私有聲明
· 頭文件示例(示例中沒有l(wèi)icense)
/* License comes here */
#ifndef TEMPLATE_HDR_H
#define TEMPLATE_HDR_H
/* Include headers */
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/* File content here */
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* TEMPLATE_HDR_H */
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