_3 standard library functions

errno.h

errno.hHeader file defines a set of error codes represent different macros should be extended for the type intinteger constant expressions.

Macro library

Macros	Explanation
extern int errno	By setting the macro system calls, some library functions in the event of error indicates what went wrong.
EDOM Domain Error	Represents a time domain error occurs, it is beyond the mathematical function-defined domains in the input parameters, errno is set to EDOM.
ERANGE Range Error	Represents a range error occurs, it is beyond the range defined in the input parameters of mathematical functions, errno is set to ERANGE.

limits.h

Macro library

The following values ​​are implementation-specific, and is defined by #define command, these values ​​are not less than the values ​​given below.

Macros	value	Explanation
CHAR_BIT	8	Define the number of bits in a byte.
SCHAR_MIN	-128	The definition of a minimum symbol characters.
SCHAR_MAX	127	Definition of a maximum of symbol characters.
UCHAR_MAX	255	Define a maximum unsigned char.
CHAR_MIN	0	Defined minimum value of type char, char indicates if negative, its value is equal to SCHAR_MIN, and 0 otherwise.
CHAR_MAX	127	Defined maximum of type char, char indicates if negative, its value is equal to SCHAR_MAX, or equal UCHAR_MAX.
MB_LEN_MAX	1	The maximum number of bytes defined in the multi-byte character.
Sःhrit_mn	-32768	Definition of a minimum short integer.
SHRT_MAX	+32767	Defines a maximum short integer.
USHRT_MAX	65535	Define a maximum unsigned short integer.
INT_MIN	-32768	Definition of a minimum integer.
INT_MAX	+32767	Defining a maximum integer.
UINT_MAX	65535	Define a maximum unsigned integer.
LONG_MIN	-2147483648	Definition of a minimum length integer.
LONG_MAX	+2147483647	Defines a maximum length integer.
ULONG_MAX	4294967295	Unsigned long a defined maximum value.

float.h

Macro library

The following values are implementation-specific, and through #definedefined instructions, these values are not less than the values given below. Please note that all instances FLTrefers to the type float, DBLrefers to the type double, LDBLit refers to the type long double.

Macros	Explanation
FLT_ROUNDS	Definition of the floating point addition of rounding modes, which can be any of the following values: -1-- not determine 0 - tends to zero 1-- to the nearest value of 2 - n tends to infinity 3 - tends to minus infinity
FLT_RADIX 2	This macro defines the base of the index indicated. Radix 2 for binary, decimal base 10, base 16 hexadecimal.
FLT_MANT_DIG DBL_MANT_DIG LDBL_MANT_DIG	These macros define the number of bits FLT_RADIX radix.
FLT_DIG 6 DBL_DIG 10 LDBL_DIG 10	These macros will not change the decimal number is rounded maximum value (base 10).
FLT_MIN_EXP DBL_MIN_EXP LDBL_MIN_EXP	These macros negative integer value defines the minimum cardinality for the index during FLT_RADIX.
FLT_MIN_10_EXP -37 DBL_MIN_10_EXP -37 LDBL_MIN_10_EXP -37	These macros define the exponential base of 10 is the minimum negative integer value.
FLT_MAX_EXP DBL_MAX_EXP LDBL_MAX_EXP	这些宏定义了基数为 FLT_RADIX 时的指数的最大整数值。
FLT_MAX_10_EXP +37 DBL_MAX_10_EXP +37 LDBL_MAX_10_EXP +37	这些宏定义了基数为 10 时的指数的最大整数值。
FLT_MAX 1E+37 DBL_MAX 1E+37 LDBL_MAX 1E+37	这些宏定义最大的有限浮点值。
FLT_EPSILON 1E-5 DBL_EPSILON 1E-9 LDBL_EPSILON 1E-9	这些宏定义了可表示的最小有效数字。
FLT_MIN 1E-37 DBL_MIN 1E-37 LDBL_MIN 1E-37	这些宏定义了最小的浮点值。

stdarg.h

库变量

变量	说明
va_list	这是一个适用于 va_start()、va_arg() 和 va_end() 这三个宏存储信息的类型。

库宏

宏	说明
void va_start(va_list ap, last_arg)	这个宏初始化 ap 变量，它与 va_arg 和 va_end 宏是一起使用的。last_arg 是最后一个传递给函数的已知的固定参数，即省略号之前的参数。
type va_arg(va_list ap, type)	这个宏检索函数参数列表中类型为 type 的下一个参数。
void va_end(va_list ap)	这个宏允许使用了 va_start 宏的带有可变参数的函数返回。如果在从函数返回之前没有调用 va_end，则结果为未定义。

stddef.h

库变量

变量	说明
ptrdiff_t	有符号整数类型，它是两个指针相减的结果。
size_t	无符号整数类型，它是 sizeof 关键字的结果。
wchar_t	是一个宽字符常量大小的整数类型。

库宏

宏	说明
NULL	是一个空指针常量的值。
offsetof(type, member-designator)	生成一个类型为 size_t 的整型常量，它是一个结构成员相对于结构开头的字节偏移量。成员是由 member-designator 给定的，结构的名称是在 type 中给定的。