C 关键字

C reserved keywords

存储类型说明符 storage-class specifier

keywords	meaning
auto	automatic duration storage-class specifier with no linkage
extern	static duration storage-class specifier with either internal or more usually external linkage
register	automatic duration storage-class specifier with no linkage. Hints that the variable will be used heavily
static	static duration storage-class specifier with internal linkage at file scope and no linkage at block scope
	static array indices in function parameter declarations (since C99)

跳转, 条件, 循环语句声明符 statement declarator

keywords	meaning
break
continue
goto
return
if	if statement
else	if statement: alternative branch
switch	switch statement
case	switch statement: case labels
default	switch statement: efault case label
	type-generic expression: as the declaration of the default generic association(since C11)
do	do-while loop
for	for loop
while	while loop
	do-while loop: terminating condition of the loop

类型声明符 type declarator

keywords	meaning
char
int
double
enum	enumeration type
float
inline	inline function specifier
struct	compound type
union
typedef
void	incomplete type
	in a function with no parameter or no return value

类型修饰符 type modifier

keywords	meaning
long	long type modifier
short	short type modifier
signed	signed type modifier
unsigned	unsigned type modifier

类型限定符 type qualifier

keywords	meaning
const	const type qualifier
restrict	restrict type qualifier
volatile	volatile type qualifier

操作符 operator

keywords	meaning
sizeof	sizeof operator

inline

1. 使用 inline 关键字声明内联函数 Inline function, 内联函数在某些情况下类似于宏, 直接将代码内嵌到调用它的父函数中
2. 编译时需要指定优化等级为 -O3 才能被内嵌, 也可以指定内嵌函数属性 #pragma always_inline 强制内嵌
3. 使用 ISO C 标准的时候，可以使用 __inline__ 关键字代替 inline 关键字

有几种情况将不内嵌，而作为普通函数调用：

1. 可变参数的函数
2. 调用 alloca 类库的函数
3. 有可变尺寸数组声明的函数
4. 非本地 goto 的函数
5. 嵌套调用的函数

const

1. 使用 const 限定符修饰形参可以防止函数修改传入的参数
2. 使用 const 限定符修饰指针和引用

参考

1. cppreference