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Suppose you need to store an integer value which can range from zero to one million. Which is the smallest type you can use? There is no general rule; it depends on the C compiler and target machine. You can use the `MIN' and `MAX' macros in limits.h to determine which type will work.
Each signed integer type has a pair of macros which give the smallest and largest values that it can hold. Each unsigned integer type has one such macro, for the maximum value; the minimum value is, of course, zero.
The values of these macros are all integer constant expressions. The
`MAX' and `MIN' macros for char
and short int
types have values of type int
. The `MAX' and
`MIN' macros for the other types have values of the same type
described by the macro—thus, ULONG_MAX
has type
unsigned long int
.
SCHAR_MIN
signed char
.
SCHAR_MAX
UCHAR_MAX
signed char
and unsigned char
, respectively.
CHAR_MIN
char
.
It's equal to SCHAR_MIN
if char
is signed, or zero
otherwise.
CHAR_MAX
char
.
It's equal to SCHAR_MAX
if char
is signed, or
UCHAR_MAX
otherwise.
SHRT_MIN
signed short int
. On most machines that the GNU C library runs on,
short
integers are 16-bit quantities.
SHRT_MAX
USHRT_MAX
signed short int
and unsigned short int
,
respectively.
INT_MIN
signed int
. On most machines that the GNU C system runs on, an int
is
a 32-bit quantity.
INT_MAX
UINT_MAX
signed int
and the type unsigned int
.
LONG_MIN
signed long int
. On most machines that the GNU C system runs on, long
integers are 32-bit quantities, the same size as int
.
LONG_MAX
ULONG_MAX
signed long int
and unsigned long int
, respectively.
LONG_LONG_MIN
signed long long int
. On most machines that the GNU C system runs on,
long long
integers are 64-bit quantities.
LONG_LONG_MAX
ULONG_LONG_MAX
signed
long long int
and unsigned long long int
, respectively.
WCHAR_MAX
wchar_t
.
See Extended Char Intro.
The header file limits.h also defines some additional constants that parameterize various operating system and file system limits. These constants are described in System Configuration.