limits.h

limits.h is the header of the general purpose standard library of C programming language which includes definitions of the characteristics of variable types. The values are implementation specific, but may not be of lower magnitude than certain specified values in a conforming C implementation.

Member constants

The "minimum-magnitude value" column is the minimum possible magnitude for this constant as specified by the standard. In particular, _MIN values represent the minimum magnitude representable in the rarely-used one's complement and sign-magnitude forms. Most implementations will have larger magnitudes for at least some of these numbers. For instance:

• Two's complement implementations have SCHAR_MIN equal to -128 (and similarly for all other _MIN values).
• 32-bit implementations will set INT_MAX equal to +2,147,483,647 (and likewise for INT_MIN and UINT_MAX)
• Unicode-supporting implementations will set MB_LEN_MAX to 4 or more.
• Many DSPs have CHAR_BIT equal to 16 or more[1][2].

Name	Description	Typical value on a PC circa 2007	ANSI standard minimum-magnitude value
CHAR_BIT	Number of bits in a byte	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	-2,147,483,648	-2,147,483,647
LONG_MAX	Maximum value for a long int	+2,147,483,647	+2,147,483,647
ULONG_MAX	Maximum value for an unsigned long int	+4,294,967,295	+4,294,967,295
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

See also

• C standard library
• Float.h - Limits on floating-point numbers

External links

• Enquire: A program for automatically generating limits.h, and for checking that the values in an existing limits.h are correct

References

• C Guide--2.5 limits.h, accessed in September 2006.