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std::numeric_limits

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C numeric limits interface
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std::numeric_limits
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Defined in header <limits>
template< class T > class numeric_limits;

The std::numeric_limits class template provides a standardized way to query various properties of arithmetic types (e.g. the largest possible value for type int is std::numeric_limits<int>::max()).

This information is provided via specializations of the std::numeric_limits template. The standard library makes available specializations for all arithmetic types (only lists the specializations for cv-unqualified arithmetic 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<char8_t>;
 (since C++20)
template<> class numeric_limits<char16_t>;
 (since C++11)
template<> class numeric_limits<char32_t>;
 (since C++11)
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>;
 (since C++11)
template<> class numeric_limits<unsigned long long>;
 (since C++11)
template<> class numeric_limits<float>;
template<> class numeric_limits<double>;
template<> class numeric_limits<long double>;

The value of each member of a specialization of std::numeric_limits on a cv-qualified type cv T is equal to the value of the corresponding member of the specialization on the unqualified type T. For example, std::numeric_limits<int>::digits is equal to std::numeric_limits<const int>::digits.

Aliases of arithmetic types (such as std::size_t or std::streamsize) may also be examined with the std::numeric_limits type traits.

Non-arithmetic standard types, such as std::complex<T> or std::nullptr_t, do not have specializations.

If the implementation defines any integer-class types, specializations of std::numeric_limits must also be provided for them.

(since C++20)

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

Contents

[edit] Template parameters

T - a type to retrieve numeric properties for

[edit] Member constants

[static]
 identifies types for which std::numeric_limits is specialized
(public static member constant) [edit]
[static]
 identifies signed types
(public static member constant) [edit]
[static]
 identifies integer types
(public static member constant) [edit]
[static]
 identifies exact types
(public static member constant) [edit]
[static]
 identifies floating-point types that can represent the special value "positive infinity"
(public static member constant) [edit]
[static]
 identifies floating-point types that can represent the special value "quiet not-a-number" (NaN)
(public static member constant) [edit]
[static]
 identifies floating-point types that can represent the special value "signaling not-a-number" (NaN)
(public static member constant) [edit]
[static]
 identifies the denormalization style used by the floating-point type
(public static member constant) [edit]
[static]
 identifies the floating-point types that detect loss of precision as denormalization loss rather than inexact result
(public static member constant) [edit]
[static]
 identifies the rounding style used by the type
(public static member constant) [edit]
[static]
 identifies the IEC 559/IEEE 754 floating-point types
(public static member constant) [edit]
[static]
 identifies types that represent a finite set of values
(public static member constant) [edit]
[static]
 identifies types that handle overflows with modulo arithmetic
(public static member constant) [edit]
[static]
 number of radix digits that can be represented without change
(public static member constant) [edit]
[static]
 number of decimal digits that can be represented without change
(public static member constant) [edit]
[static] (C++11)
 number of decimal digits necessary to differentiate all values of this type
(public static member constant) [edit]
[static]
 the radix or integer base used by the representation of the given type
(public static member constant) [edit]
[static]
 one more than the smallest negative power of the radix that is a valid normalized floating-point value
(public static member constant) [edit]
[static]
 the smallest negative power of ten that is a valid normalized floating-point value
(public static member constant) [edit]
[static]
 one more than the largest integer power of the radix that is a valid finite floating-point value
(public static member constant)