Difference between revisions of "cpp/types/climits"
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===Limits of integer types=== | ===Limits of integer types=== | ||
Revision as of 06:07, 4 June 2021
See also std::numeric_limits interface.
| Defined in header
<cstdint> | |
| PTRDIFF_MIN (C++11) |
minimum value of std::ptrdiff_t (macro constant) |
| PTRDIFF_MAX (C++11) |
maximum value of std::ptrdiff_t (macro constant) |
| SIZE_MAX (C++11) |
maximum value of std::size_t (macro constant) |
| SIG_ATOMIC_MIN (C++11) |
minimum value of std::sig_atomic_t (macro constant) |
| SIG_ATOMIC_MAX (C++11) |
maximum value of std::sig_atomic_t (macro constant) |
| WCHAR_MIN (C++11) |
minimum value of wchar_t (macro constant) |
| WCHAR_MAX (C++11) |
maximum value of wchar_t (macro constant) |
| WINT_MIN (C++11) |
minimum value of std::wint_t (macro constant) |
| WINT_MAX (C++11) |
maximum value of std::wint_t (macro constant) |
Note: a freestanding implementation may lack std::sig_atomic_t and/or std::wint_t typedef names, in which case the SIG_ATOMIC_* and/or WINT_* macros are correspondingly absent.
Limits of integer types
| Defined in header
<climits> | |
| CHAR_BIT |
number of bits in a byte (macro constant) |
| MB_LEN_MAX |
maximum number of bytes in a multibyte character (macro constant) |
| CHAR_MIN |
minimum value of char (macro constant) |
| CHAR_MAX |
maximum value of char (macro constant) |
| SCHAR_MINSHRT_MININT_MINLONG_MINLLONG_MIN (C++11) |
minimum value of signed char, short, int, long and long long respectively (macro constant) |
| SCHAR_MAXSHRT_MAXINT_MAXLONG_MAXLLONG_MAX (C++11) |
maximum value of signed char, short, int, long and long long respectively (macro constant) |
| UCHAR_MAXUSHRT_MAXUINT_MAXULONG_MAXULLONG_MAX (C++11) |
maximum value of unsigned char, unsigned short, unsigned int, unsigned long and unsigned long long respectively (macro constant) |
Note: 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.
Limits of floating point types
| Defined in header
<cfloat> | |
| FLT_RADIX |
the radix (integer base) used by the representation of all three floating-point types (macro constant) |
| DECIMAL_DIG (C++11) |
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 (see also std::numeric_limits::max_digits10) (macro constant) |
| FLT_DECIMAL_DIGDBL_DECIMAL_DIGLDBL_DECIMAL_DIG (C++17) |
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 (see also std::numeric_limits::max_digits10). Defined to at least 6, 10, and 10 respectively, or 9 for IEEE float and 17 for IEEE double. (macro constant) |
| FLT_MINDBL_MINLDBL_MIN |
minimum normalized positive value of float, double and long double respectively (macro constant) |
| FLT_TRUE_MINDBL_TRUE_MINLDBL_TRUE_MIN (C++17) |
minimum positive value of float, double and long double respectively (macro constant) |
| FLT_MAXDBL_MAXLDBL_MAX |
maximum finite value of float, double and long double respectively (macro constant) |
| FLT_EPSILONDBL_EPSILONLDBL_EPSILON |
difference between 1.0 and the next representable value for float, double and long double respectively (macro constant) |
| FLT_DIGDBL_DIGLDBL_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 std::numeric_limits::digits10 for explanation) (macro constant) |
| FLT_MANT_DIGDBL_MANT_DIGLDBL_MANT_DIG |
number of base FLT_RADIX digits that can be represented without losing precision for float, double and long double respectively (macro constant) |
| FLT_MIN_EXPDBL_MIN_EXPLDBL_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) |
| FLT_MIN_10_EXPDBL_MIN_10_EXPLDBL_MIN_10_EXP |
minimum negative integer such that 10 raised to that power is a normalized float, double and long double respectively (macro constant) |
| FLT_MAX_EXPDBL_MAX_EXPLDBL_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) |
| FLT_MAX_10_EXPDBL_MAX_10_EXPLDBL_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) |
| default rounding mode of floating-point arithmetic (macro constant) | |
| (C++11) |
specifies in what precision all arithmetic operations are done (macro constant) |
| FLT_HAS_SUBNORMDBL_HAS_SUBNORMLDBL_HAS_SUBNORM (C++17) |
specifies whether the type supports subnormal (denormal) numbers: -1 – indeterminable, 0 – absent, 1 – present (macro constant) |
See also
- Fixed width integer types
- Arithmetic types
- C++ type system overview
- Type support (basic types, RTTI, type traits)
| C documentation for Numeric limits
|
