Numeric limits
From cppreference.com
Limits of integer types
Limits of core language integer types |
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Defined in header
<limits.h>
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BOOL_WIDTH
(C23)
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bit width of
_Bool
(macro constant) |
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CHAR_BIT
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bit width of byte
(macro constant) |
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MB_LEN_MAX
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maximum number of bytes in a multibyte character
(macro constant) |
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CHAR_WIDTH
(C23)
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bit width of
char
, same as
CHAR_BIT
(macro constant) |
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CHAR_MIN
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minimum value of
char
(macro constant) |
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CHAR_MAX
|
maximum value of
char
(macro constant) |
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SCHAR_WIDTH
SHRT_WIDTH
INT_WIDTH
LONG_WIDTH
LLONG_WIDTH
(C23)
(C23)
(C23)
(C23)
(C23)
|
bit width of
signed
char
,
short
,
int
,
long
, and
long
long
respectively
(macro constant) |
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SCHAR_MIN
SHRT_MIN
INT_MIN
LONG_MIN
LLONG_MIN
(C99)
|
minimum value of
signed
char
,
short
,
int
,
long
and
long
long
respectively
(macro constant) |
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SCHAR_MAX
SHRT_MAX
INT_MAX
LONG_MAX
LLONG_MAX
(C99)
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maximum value of
signed
char
,
short
,
int
,
long
and
long
long
respectively
(macro constant) |
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UCHAR_WIDTH
USHRT_WIDTH
UINT_WIDTH
ULONG_WIDTH
ULLONG_WIDTH
(C23)
(C23)
(C23)
(C23)
(C23)
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bit width of
unsigned
char
,
unsigned
short
,
unsigned
int
,
unsigned
long
, and
unsigned
long
long
respectively
(macro constant) |
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UCHAR_MAX
USHRT_MAX
UINT_MAX
ULONG_MAX
ULLONG_MAX
(C99)
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maximum value of
unsigned
char
,
unsigned
short
,
unsigned
int
,
unsigned long and unsigned long long respectively (macro constant) |
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BITINT_MAXWIDTH
(C23)
|
maximum width
N
supported by the declaration of a bit-precise integer in the type specifier
_BitInt
(
N
)
, greater than or equal to
ULLONG_WIDTH
(macro constant) |
Limits of library type aliases |
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Defined in header
<stdint.h>
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PTRDIFF_WIDTH
(C23)
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bit width of object of
ptrdiff_t
type
(macro constant) |
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PTRDIFF_MIN
(C99)
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minimum value of
ptrdiff_t
(macro constant) |
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PTRDIFF_MAX
(C99)
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maximum value of
ptrdiff_t
(macro constant) |
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SIZE_WIDTH
(C23)
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bit width of object of
size_t
type
(macro constant) |
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SIZE_MAX
(C99)
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maximum value of
size_t
(macro constant) |
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SIG_ATOMIC_WIDTH
(C23)
|
bit width of object of
sig_atomic_t
type
(macro constant) |
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SIG_ATOMIC_MIN
(C99)
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minimum value of
sig_atomic_t
(macro constant) |
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SIG_ATOMIC_MAX
(C99)
|
maximum value of
sig_atomic_t
(macro constant) |
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WINT_WIDTH
(C23)
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bit width of object of
wint_t
type
(macro constant) |
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WINT_MIN
(C99)
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minimum value of
wint_t
(macro constant) |
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WINT_MAX
(C99)
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maximum value of
wint_t
(macro constant) |
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Defined in header
<wchar.h>
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Defined in header
<stdint.h>
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WCHAR_WIDTH
(C23)
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bit width of object of
wchar_t
type
(macro constant) |
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WCHAR_MIN
(C99)
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minimum value of
wchar_t
(macro constant) |
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WCHAR_MAX
(C99)
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maximum value of
wchar_t
(macro constant) |
Notes
The types of these constants, other than
CHAR_BIT
and
MB_LEN_MAX
, are required to match the results of the
integral promotions
as applied to objects of the types they describe:
CHAR_MAX
may have type
int
or
unsigned
int
, but never
char
. Similarly
USHRT_MAX
may not be of an unsigned type: its type may be
int
.
A freestanding implementation may lack
sig_atomic_t
and/or
wint_t
typedef names, in which case the
SIG_ATOMIC_*
and/or
WINT_*
macros are correspondingly absent.
Example
Run this code
#include <limits.h> #include <stdint.h> #include <stdio.h> int main(void) { printf("CHAR_BIT = %d\n", CHAR_BIT); printf("MB_LEN_MAX = %d\n\n", MB_LEN_MAX); printf("CHAR_MIN = %+d\n", CHAR_MIN); printf("CHAR_MAX = %+d\n", CHAR_MAX); printf("SCHAR_MIN = %+d\n", SCHAR_MIN); printf("SCHAR_MAX = %+d\n", SCHAR_MAX); printf("UCHAR_MAX = %u\n\n", UCHAR_MAX); printf("SHRT_MIN = %+d\n", SHRT_MIN); printf("SHRT_MAX = %+d\n", SHRT_MAX); printf("USHRT_MAX = %u\n\n", USHRT_MAX); printf("INT_MIN = %+d\n", INT_MIN); printf("INT_MAX = %+d\n", INT_MAX); printf("UINT_MAX = %u\n\n", UINT_MAX); printf("LONG_MIN = %+ld\n", LONG_MIN); printf("LONG_MAX = %+ld\n", LONG_MAX); printf("ULONG_MAX = %lu\n\n", ULONG_MAX); printf("LLONG_MIN = %+lld\n", LLONG_MIN); printf("LLONG_MAX = %+lld\n", LLONG_MAX); printf("ULLONG_MAX = %llu\n\n", ULLONG_MAX); printf("PTRDIFF_MIN = %td\n", PTRDIFF_MIN); printf("PTRDIFF_MAX = %+td\n", PTRDIFF_MAX); printf("SIZE_MAX = %zu\n", SIZE_MAX); printf("SIG_ATOMIC_MIN = %+jd\n",(intmax_t)SIG_ATOMIC_MIN); printf("SIG_ATOMIC_MAX = %+jd\n",(intmax_t)SIG_ATOMIC_MAX); printf("WCHAR_MIN = %+jd\n",(intmax_t)WCHAR_MIN); printf("WCHAR_MAX = %+jd\n",(intmax_t)WCHAR_MAX); printf("WINT_MIN = %jd\n", (intmax_t)WINT_MIN); printf("WINT_MAX = %jd\n", (intmax_t)WINT_MAX); }
Possible output:
CHAR_BIT = 8 MB_LEN_MAX = 16 CHAR_MIN = -128 CHAR_MAX = +127 SCHAR_MIN = -128 SCHAR_MAX = +127 UCHAR_MAX = 255 SHRT_MIN = -32768 SHRT_MAX = +32767 USHRT_MAX = 65535 INT_MIN = -2147483648 INT_MAX = +2147483647 UINT_MAX = 4294967295 LONG_MIN = -9223372036854775808 LONG_MAX = +9223372036854775807 ULONG_MAX = 18446744073709551615 LLONG_MIN = -9223372036854775808 LLONG_MAX = +9223372036854775807 ULLONG_MAX = 18446744073709551615 PTRDIFF_MIN = -9223372036854775808 PTRDIFF_MAX = +9223372036854775807 SIZE_MAX = 18446744073709551615 SIG_ATOMIC_MIN = -2147483648 SIG_ATOMIC_MAX = +2147483647 WCHAR_MIN = -2147483648 WCHAR_MAX = +2147483647 WINT_MIN = 0 WINT_MAX = 4294967295
Limits of floating-point types
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Defined in header
<float.h>
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FLT_RADIX
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the radix (integer base) used by the representation of all three floating-point types
(macro constant) |
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DECIMAL_DIG
(C99)
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conversion from
long
double
to decimal with at least
DECIMAL_DIG
digits and back to
long
double
is the identity conversion: this is the decimal precision required to serialize/deserialize a
long
double
(macro constant) |
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FLT_DECIMAL_DIG
DBL_DECIMAL_DIG
LDBL_DECIMAL_DIG
(C11)
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conversion from
float
/
double
/
long
double
to decimal with at least
FLT_DECIMAL_DIG
/
DBL_DECIMAL_DIG
/
LDBL_DECIMAL_DIG
digits and back is the identity conversion: this is the decimal precision required to serialize/deserialize a floating-point value. Defined to at least
6
,
10
, and
10
respectively, or
9
for IEEE float and
17
for IEEE double (see also the C++ analog:
max_digits10
)
(macro constant) |
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FLT_MIN
DBL_MIN
LDBL_MIN
|
minimum, normalized, positive value of
float
,
double
and
long
double
respectively
(macro constant) |
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FLT_TRUE_MIN
DBL_TRUE_MIN
LDBL_TRUE_MIN
(C11)
|
minimum positive value of
float
,
double
and
long
double
respectively
(macro constant) |
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FLT_MAX
DBL_MAX
LDBL_MAX
|
maximum finite value of
float
,
double
and
long
double
respectively
(macro constant) |
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FLT_EPSILON
DBL_EPSILON
LDBL_EPSILON
|
absolute value difference between
1.0
and the next representable value for
float
,
double
and
long
double
respectively
(macro constant) |
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FLT_DIG
DBL_DIG
LDBL_DIG
|
number of decimal digits that are guaranteed to be preserved in text →
float
/
double
/
long
double
→ text roundtrip without change due to rounding or overflow (see the C++ analog
digits10
for detail)
(macro constant) |
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FLT_MANT_DIG
DBL_MANT_DIG
LDBL_MANT_DIG
|
number of base-
FLT_RADIX
digits that are in the floating-point mantissa and that can be represented without losing precision for
float
,
double
and
long
double
respectively
(macro constant) |
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FLT_MIN_EXP
DBL_MIN_EXP
LDBL_MIN_EXP
|
minimum negative integer such that
FLT_RADIX
raised by power one less than that integer is a normalized
float
,
double
and
long
double
respectively
(macro constant) |
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FLT_MIN_10_EXP
DBL_MIN_10_EXP
LDBL_MIN_10_EXP
|
minimum negative integer such that 10 raised to that power is a normalized
float
,
double
and
long
double
respectively
(macro constant) |
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FLT_MAX_EXP
DBL_MAX_EXP
LDBL_MAX_EXP
|
maximum positive integer such that
FLT_RADIX
raised by power one less than that integer is a representable finite
float
,
double
and
long
double
respectively
(macro constant) |
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FLT_MAX_10_EXP
DBL_MAX_10_EXP
LDBL_MAX_10_EXP
|
maximum positive integer such that 10 raised to that power is a representable finite
float
,
double
and
long
double
respectively
(macro constant) |
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rounding mode of floating-point arithmetic
(macro constant) |
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(C99)
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use of extended precision for intermediate results:
0 – not used, 1 – double is used instead of float , 2 – long double is used (macro constant) |
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FLT_HAS_SUBNORM
DBL_HAS_SUBNORM
LDBL_HAS_SUBNORM
(C11)
(deprecated in C23)
|
whether the type supports subnormal (
denormal
) numbers:
- 1 – indeterminable, 0 – absent, 1 – present (macro constant) |
Example
Run this code
#include <float.h> #include <math.h> #include <stdio.h> int main(void) { printf("DECIMAL_DIG = %d\n", DECIMAL_DIG); printf("FLT_DECIMAL_DIG = %d\n", FLT_DECIMAL_DIG); printf("FLT_RADIX = %d\n", FLT_RADIX); printf("FLT_MIN = %e\n", FLT_MIN); printf("FLT_MAX = %e\n", FLT_MAX); printf("FLT_EPSILON = %e\n", FLT_EPSILON); printf("FLT_DIG = %d\n", FLT_DIG); printf("FLT_MANT_DIG = %d\n", FLT_MANT_DIG); printf("FLT_MIN_EXP = %d\n", FLT_MIN_EXP); printf("FLT_MIN_10_EXP = %d\n", FLT_MIN_10_EXP); printf("FLT_MAX_EXP = %d\n", FLT_MAX_EXP); printf("FLT_MAX_10_EXP = %d\n", FLT_MAX_10_EXP); printf("FLT_ROUNDS = %d\n", FLT_ROUNDS); printf("FLT_EVAL_METHOD = %d\n", FLT_EVAL_METHOD); printf("FLT_HAS_SUBNORM = %d\n", FLT_HAS_SUBNORM); }
Possible output:
DECIMAL_DIG = 37 FLT_DECIMAL_DIG = 9 FLT_RADIX = 2 FLT_MIN = 1.175494e-38 FLT_MAX = 3.402823e+38 FLT_EPSILON = 1.192093e-07 FLT_DIG = 6 FLT_MANT_DIG = 24 FLT_MIN_EXP = -125 FLT_MIN_10_EXP = -37 FLT_MAX_EXP = 128 FLT_MAX_10_EXP = 38 FLT_ROUNDS = 1 FLT_EVAL_METHOD = 1 FLT_HAS_SUBNORM = 1
References
- C23 standard (ISO/IEC 9899:2024):
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- 5.2.4.2 Numerical limits (p: TBD)
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- 7.22.3 Limits of other integer types (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
-
- 5.2.4.2 Numerical limits (p: 20-27)
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- 7.20.3 Limits of other integer types (p: 215-216)
- C11 standard (ISO/IEC 9899:2011):
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- 5.2.4.2 Numerical limits (p: 26-34)
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- 7.20.3 Limits of other integer types (p: 293-294)
- C99 standard (ISO/IEC 9899:1999):
-
- 5.2.4.2 Numerical limits (p: 21-28)
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- 7.18.3 Limits of other integer types (p: 259-260)
- C89/C90 standard (ISO/IEC 9899:1990):
-
- 2.2.4.2 Numerical limits
See also
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C++ documentation
for
C numeric limits interface
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