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 .

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
`LONG_MIN`	Minimum value for a long int	64 bit compiler	−9,223,372,036,854,775,808	≤−2,147,483,647
`LONG_MAX`	Maximum value for a long int	32 bit compiler	+2,147,483,647	≥+2,147,483,647
`LONG_MAX`	Maximum value for a long int	64 bit compiler	+9,223,372,036,854,775,807	≥+2,147,483,647
`ULONG_MAX`	Maximum value for an unsigned long int	32 bit compiler	+4,294,967,295	≥+4,294,967,295
`ULONG_MAX`	Maximum value for an unsigned long int	64 bit compiler	+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		≤−9,223,372,036,854,775,807
`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

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