limits.h

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C Standard Library headers

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.

Contents

[edit] 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

[edit] See also

[edit] External links

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

[edit] References