limits.h

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

The C99 standard also specifies the stdint.h file, which provides names and limits for explicitly-sized platform-independent integer datatypes (e.g. int32_t for a 32-bit signed integer).

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 32 bit executable/compiler (ca. 1995 until now)	Typical value on a 64 bit executable/compiler (ca. 2008(?))	ANSI standard minimum- or maximum magnitude value
CHAR_BIT	Number of bits in a char	8	8	≥+8
SCHAR_MIN	Minimum value for a signed char	–128	–128	≤–127
SCHAR_MAX	Maximum value for a signed char	+127	+127	≥+127
UCHAR_MAX	Maximum value for an unsigned char	+255	+255	≥+255
CHAR_MIN	Minimum value for a char	–128	–128	≤–127 (if char is represented as a signed char; otherwise ≤0)
CHAR_MAX	Maximum value for a char	+127	+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	varies, usually at least 4	≥+1
SHRT_MIN	Minimum value for a short int	–32,768	–32,768	≤–32,767
SHRT_MAX	Maximum value for a short int	+32,767	+32,767	≥+32,767
USHRT_MAX	Maximum value for an unsigned short int	+65,535	+65,535	≥+65,535
INT_MIN	Minimum value for an int	–2,147,483,648	–2,147,483,648	≤–32,767
INT_MAX	Maximum value for an int	+2,147,483,647	+2,147,483,647	≥+32,767
UINT_MAX	Maximum value for an unsigned int	+4,294,967,295	+4,294,967,295	≥+65,535
LONG_MIN	Minimum value for a long int	–2,147,483,648	–9,223,372,036,854,775,808	≤–2,147,483,647
LONG_MAX	Maximum value for a long int	+2,147,483,647	+9,223,372,036,854,775,807	≥+2,147,483,647
ULONG_MAX	Maximum value for an unsigned long int	+4,294,967,295	+18,446,744,073,709,551,615	≥+4,294,967,295
LLONG_MIN	Minimum value for a long long int	–9,223,372,036,854,775,808	–9,223,372,036,854,775,808	≤-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	≥+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	≥+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.