std::numeric_limits

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Type support
std::numeric_limits
Static constants numeric_limits::is_specialized numeric_limits::is_signed numeric_limits::is_integer numeric_limits::is_exact numeric_limits::has_infinity numeric_limits::has_quiet_NaN numeric_limits::has_signaling_NaN numeric_limits::has_denorm numeric_limits::has_denorm_loss numeric_limits::round_style numeric_limits::is_iec559 numeric_limits::is_bounded numeric_limits::is_modulo numeric_limits::digits numeric_limits::digits10 numeric_limits::max_digits10 (C++11) numeric_limits::radix numeric_limits::min_exponent numeric_limits::min_exponent10 numeric_limits::max_exponent numeric_limits::max_exponent10 numeric_limits::traps numeric_limits::tinyness_before Static member functions numeric_limits::min numeric_limits::lowest (C++11) numeric_limits::max numeric_limits::epsilon numeric_limits::round_error numeric_limits::infinity numeric_limits::quiet_NaN numeric_limits::signaling_NaN numeric_limits::denorm_min Helper types float_round_style float_denorm_style

Defined in header <limits>
template< class T > class numeric_limits;

The numeric_limits class template provides a standardized way to query about various properties of representation of fundamental types. This information is provided via specializations of the numeric_limits template. The standard library makes available specializations for all fundamental types:

Defined in header <limits>
template<> class numeric_limits<bool>; template<> class numeric_limits<char>; template<> class numeric_limits<signed char>; template<> class numeric_limits<unsigned char>; template<> class numeric_limits<wchar_t>; template<> class numeric_limits<char16_t>;   // C++11 feature template<> class numeric_limits<char32_t>;   // C++11 feature template<> class numeric_limits<short>; template<> class numeric_limits<unsigned short>; template<> class numeric_limits<int>; template<> class numeric_limits<unsigned int>; template<> class numeric_limits<long>; template<> class numeric_limits<unsigned long>; template<> class numeric_limits<long long>; template<> class numeric_limits<unsigned long long>; template<> class numeric_limits<float>; template<> class numeric_limits<double>; template<> class numeric_limits<long double>;

The standard library types that are aliases of fundamental types (such as std::size_t or std::streamsize may also be examined with the std::numeric_limits type traits.

Implementations may provide specializations of std::numeric_limits for implementation-specific types: e.g. GCC provides std::numeric_limits<__int128>. Libraries may add specializations for library-provided types, e.g. OpenEXR provides std::numeric_limits<half> for a 16-bit floating-point type.

Contents 1 Member constants 2 Member functions 3 Helper classes 4 Relationship with macro constants of C library

[edit] Member constants

is_specialized	identifies types for which std::numeric_limits is specialized (public static member constant)
is_signed	identifies signed types (public static member constant)
is_integer	identifies integer types (public static member constant)
is_exact	identifies exact types (public static member constant)
has_infinity	identifies floating-point types that can represent the special value "positive infinity" (public static member constant)
has_quiet_NaN	identifies floating-point types that can represent the special value "quiet not-a-number" (NaN) (public static member constant)
has_signaling_NaN	identifies floating-point types that can represent the special value "signaling not-a-number" (NaN) (public static member constant)
has_denorm	identifies the denormalization style used by the floating-point type (public static member constant)
has_denorm_loss	identifies the floating-point types that detect loss of precision as denormalization loss rather than inexact result (public static member constant)
round_style	identifies the rounding style used by the type (public static member constant)
is_iec559	identifies the IEC 559/IEEE 754 floating-point types (public static member constant)
is_bounded	identifies types that represent a finite set of values (public static member constant)
is_modulo	identifies types that handle overflows with modulo arithmetic (public static member constant)
digits	number of radix digits that can be represented without change (public static member constant)
digits10	number of decimal digits that can be represented without change (public static member constant)
max_digits10 (C++11)	number of decimal digits necessary to differentiate all values of this type (public static member constant)
radix	the radix or integer base used by the representation of the given type (public static member constant)
min_exponent	one more than the smallest negative power of the radix that is a valid normalized floating-point value (public static member constant)
min_exponent10	the smallest negative power of ten that is a valid normalized floating-point value (public static member constant)
max_exponent	one more than the largest integer power of the radix that is a valid finite floating-point value (public static member constant)
max_exponent10	the largest integer power of 10 that is a valid finite floating-point value (public static member constant)
traps	identifies types which can cause arithmetic operations to trap (public static member constant)
tinyness_before	identifies floating-point types that detect tinyness before rounding (public static member constant)

[edit] Member functions

min [static]	returns the smallest finite value of the given type (public static member function)
lowest [static] (C++11)	returns the lowest finite value of the given type (public static member function)
max [static]	returns the largest finite value of the given type (public static member function)
epsilon [static]	returns the difference between 1.0 and the next representable value of the given floating-point type (public static member function)
round_error [static]	returns the maximum rounding error of the given floating-point type (public static member function)
infinity [static]	returns the positive infinity value of the given floating-point type (public static member function)
quiet_NaN [static]	returns the quiet NaN value of the given floating-point type (public static member function)
signaling_NaN [static]	returns the signaling NaN value of the given floating-point type (public static member function)
denorm_min [static]	returns the smallest positive subnormal value of the given floating-point type (public static member function)

[edit] Helper classes

float_round_style	indicates floating-point rounding modes (class)
float_denorm_style	indicates floating-point denormalization modes (class)

[edit] Relationship with macro constants of C library

Specialization	Members
	min()	lowest() (C++11)	max()	epsilon()	digits()	digits10()	min_exponent()	min_exponent10()	max_exponent()	max_exponent10()	radix
numeric_limits< bool >											2
numeric_limits< char >	CHAR_MIN	CHAR_MIN	CHAR_MAX								2
numeric_limits< signed char >	SCHAR_MIN	SCHAR_MIN	SCHAR_MAX								2
numeric_limits< unsigned char >	0	0	UCHAR_MAX								2
numeric_limits< wchar_t >	WCHAR_MIN	WCHAR_MIN	WCHAR_MAX								2
numeric_limits< char16_t >	0	0	UINT_LEAST16_MAX								2
numeric_limits< char32_t >	0	0	UINT_LEAST32_MAX								2
numeric_limits< short >	SHRT_MIN	SHRT_MIN	SHRT_MAX								2
numeric_limits< signed short >
numeric_limits< unsigned short >	USHRT_MIN	USHRT_MIN	USHRT_MAX								2
numeric_limits< int >	INT_MIN	INT_MIN	INT_MAX								2
numeric_limits< signed int >
numeric_limits< unsigned int >	0	0	UINT_MAX								2
numeric_limits< long >	LONG_MIN	LONG_MIN	LONG_MAX								2
numeric_limits< signed long >
numeric_limits< unsigned long >	0	0	ULONG_MAX								2
numeric_limits< long long >	LLONG_MIN	LLONG_MIN	LLONG_MAX								2
numeric_limits< signed long long >
numeric_limits< unsigned long long >	0	0	ULLONG_MAX								2
numeric_limits< float >	FLT_MIN	-FLT_MAX	FLT_MAX	FLT_EPSILON	FLT_MANT_DIG	FLT_DIG	FLT_MIN_EXP	FLT_MIN_10_EXP	FLT_MAX_EXP	FLT_MAX_10_EXP	FLT_RADIX
numeric_limits< double >	DBL_MIN	-DBL_MAX	DBL_MAX	DBL_EPSILON	DBL_MANT_DIG	DBL_DIG	DBL_MIN_EXP	DBL_MIN_10_EXP	DBL_MAX_EXP	DBL_MAX_10_EXP	FLT_RADIX
numeric_limits< long double >	LDBL_MIN	-LDBL_MAX	LDBL_MAX	LDBL_EPSILON	LDBL_MANT_DIG	LDBL_DIG	LDBL_MIN_EXP	LDBL_MIN_10_EXP	LDBL_MAX_EXP	LDBL_MAX_10_EXP	FLT_RADIX