C Programming/limits.h

limits.h 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> header 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		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	16 bit compiler	-32768 or −2,147,483,648	≤−32,767
		32 or 64 bit compiler	−2,147,483,648
INT_MAX	Maximum value for an int	16 bit compiler	+32,767 or +2,147,483,647	≥+32,767
		32 or 64 bit compiler	+2,147,483,647
UINT_MAX	Maximum value for an unsigned int	16 bit compiler	+65,535 or +4,294,967,295	≥+65,535
		32 or 64 bit compiler	+4,294,967,295
LONG_MIN	Minimum value for a long int	16 or 32 bit compiler	−2,147,483,648	≤−2,147,483,647
		64 bit compiler	−2,147,483,648 or −9,223,372,036,854,775,808
LONG_MAX	Maximum value for a long int	16 or 32 bit compiler	+2,147,483,647	≥+2,147,483,647
		64 bit compiler	+2,147,483,647 or +9,223,372,036,854,775,807
ULONG_MAX	Maximum value for an unsigned long int	16 or 32 bit compiler	+4,294,967,295	≥+4,294,967,295
		64 bit compiler	+4,294,967,295 or +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

References

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

External links

• C++ reference for implementation defined numeric constants inherited from C