头文件：limits.h、float.h

C语言的数据类型有四种：整形、浮点型、指针、聚合类型（数组、结构等），其中整形家族的变量包括：char, int, short, long, enum等。浮点数家族包括float, double等。

limits.h头文件对整形家族变量范围进行了宏定义。float.h定义了FLT_MAX, FLT_MIN, DBL_MAX, DBL_MIN。下面这张表搬运自维基百科。

Name	Description	Typical value		ANSI standard minimum- or maximum magnitude value
CHAR_BIT	Number of bits in a char	8		≥+8
SCHAR_MIN	Minimum value for a signed char	–128		≤–127
SCHAR_MAX	Maximum value for a signed char	+127		≥+127
UCHAR_MAX	Maximum value for an unsigned char	+255		≥+255
CHAR_MIN	Minimum value for a char	–128		≤–127 (if char is represented as a signed char; otherwise ≤0)
CHAR_MAX	Maximum value for a char	+127		≥+127 (if char is represented as a signed char; otherwise ≥+255)
MB_LEN_MAX	Maximum multi byte length of a character across all locales	varies, usually at least 4		≥+1
SHRT_MIN	Minimum value for a short int	–32,768		≤–32,767
SHRT_MAX	Maximum value for a short int	+32,767		≥+32,767
USHRT_MAX	Maximum value for an unsigned short int	+65,535		≥+65,535
INT_MIN	Minimum value for an int	–2,147,483,648		≤–32,767
INT_MAX	Maximum value for an int	+2,147,483,647		≥+32,767
UINT_MAX	Maximum value for an unsigned int	+4,294,967,295		≥+65,535
LONG_MIN	Minimum value for a long int	32 bit compiler	–2,147,483,648	≤–2,147,483,647
		64 bit compiler	–9,223,372,036,854,775,808
LONG_MAX	Maximum value for a long int	32 bit compiler	+2,147,483,647	≥+2,147,483,647
		64 bit compiler	+9,223,372,036,854,775,807
ULONG_MAX	Maximum value for an unsigned long int	32 bit compiler	+4,294,967,295	≥+4,294,967,295
		64 bit compiler	+18,446,744,073,709,551,615
LLONG_MIN	Minimum value for a long long int	–9,223,372,036,854,775,808		≤-9,223,372,036,854,775,807
LLONG_MAX	Maximum value for a long long int	+9,223,372,036,854,775,807		≥+9,223,372,036,854,775,807
ULLONG_MAX	Maximum value for an unsigned long long int	+18,446,744,073,709,551,615		≥+18,446,744,073,709,551,615