【游戏编程扯淡精粹】《C语言现代方法》汇总

• 成员是数组，可以访问某个索引的偏移
• 使用offset的意义在于，编译器对于成员会自己重排保证对齐
  • 所以offset不一定等于你自己手算的

// @zolo
// $ ./01.exe
// 0
// 4
// 8
// 12
#include 
#include 
struct s {
    char a;
    int b[2];
    float c;
};
int main(void)
{
    printf("%ldn", offsetof(struct s, a));
    printf("%ldn", offsetof(struct s, b[0]));
    printf("%ldn", offsetof(struct s, b[1]));
    printf("%ldn", offsetof(struct s, c));
    
}

搜了stdio.h

• windows sdk
• visual studio
• mingw

宏隐藏函数指的是，头提供的api函数是宏函数assert，宏assert内部调用了__assert（你可以调用，但是不应该调用）

使用宏隐藏时，函数当然必须在宏前声明

• 因为宏调用了函数
• 如果反过来，assert会展开__assert

# define assert(expr)							
  ((expr)								
   ? __ASSERT_VOID_CAST (0)						
   : __assert_fail (__STRING(expr), __FILE__, __LINE__, __ASSERT_FUNCTION))



extern void __assert (const char *__assertion, const char *__file, int __line)
     __THROW __attribute__ ((__noreturn__));

大致意思就是，这些标识符你不要用作自己的标识符

complex.h

    Function names:
    cerf
    cerfc
    cexp2
    cexpm1
    clog10
    clog1p
    clog2
    clgamma
    ctgamma

    And the same names suffixed with f or l.

ctype.h

    Function names:
    Any names that begin with is or to, and a lowercase letter may be added
    to the declarations in the ctype.h header.

errno.h
    Macro names:
    Names that begin with E and a digit, or E and an uppercase letter.

inttypes.h
    Macro names:
    Names that begin with PRI or SCN followed by any lowercase letter.
    X may be added to any macros defined in the inttypes.h header.

locale.h
    Macro names:
    Names that begin with LC_ and an uppercase letter.

signal.h
    Macro names:
    Names that begin with either SIG and an uppercase letter or SIG_ and an
    uppercase letter.

stdint.h
    Typedef names:
    Names beginning with int or unit and ending with _t.

    Macro names:
    Names begging with INT or UINT and ending with _MAX, _MIN, or _C.

stdio.h
    Lowercase letters may be added to the conversion specifiers and length
    modifiers in fprintf and fscanf. Other characters may be used in extensions.

stdlib.h
    Function names:
    Names that begin with str and a lowercase letter.

string.h
    Function names:
    Names that begin with str, mem, or wcs and a lowercase letter.

wchar.h
    Function names:
    Names that begin with wcs and a lowecase letter.

    Lowercase letters may be added to the conversion specifiers and length
    modifiers in fwprintf and fwscanf. Other characters may be used in
    extensions.

wctype.h
    Function names:
    Names that begin with is or to and a lowercase letter.

#define islower(c) ((c) >= 'a' && (c) <= 'z')

标准

• 谨慎全面地使用括号保护好
• 每个参数仅被求值一次

这种写法，参数c出现了两次
因此如果c是一个有副作用的表达式，表达式会引起两次副作用

比如islower(c++)