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Difference between revisions of "cpp/header/limits"

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< cpp‎ | header
m (Update links.)
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===Declarations===
 
===Declarations===
 
{{dsc begin}}
 
{{dsc begin}}
−
{{dsc inc | cpp/types/dsc numeric_limits}}
+
{{dsc inc|cpp/types/dsc numeric_limits}}
−
{{dsc inc | cpp/types/numeric_limits/dsc float_round_style}}
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{{dsc inc|cpp/types/numeric_limits/dsc float_round_style}}
−
{{dsc inc | cpp/types/numeric_limits/dsc float_denorm_style}}
+
{{dsc inc|cpp/types/numeric_limits/dsc float_denorm_style}}
 
{{dsc end}}
 
{{dsc end}}
  
 
===Synopsis===
 
===Synopsis===
 +
{{cpp/synopsis/limits}}
  
−
{{source|
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===Defect reports===
 +
{{dr list begin}}
 +
{{dr list item|wg=lwg|dr=184|std=C++98|before=the definition of the specialization {{c/core|std::numeric_limits<bool>}} was not provided|after=provided}}
 +
{{dr list item|wg=lwg|dr=559|std=C++98|before=the {{lc|std::numeric_limits}} specializations of cv-qualified<br>arithmetic types were missing in the synopsis|after=added}}
 +
{{dr list end}}
  
−
namespace std {
+
{{langlinks|es|ja|ru|zh}}
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    template<class T> class numeric_limits;
+
−
 
+
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    enum float_round_style {
+
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        round_indeterminate        {{=}} -1,
+
−
        round_toward_zero          {{=}}  0,
+
−
        round_to_nearest            {{=}}  1,
+
−
        round_toward_infinity      {{=}}  2,
+
−
        round_toward_neg_infinity  {{=}}  3,
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    };
+
−
 
+
−
    enum float_denorm_style {
+
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        denorm_indeterminate {{=}} -1,
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        denorm_absent        {{=}}  0,
+
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        denorm_present      {{=}}  1
+
−
    };
+
−
 
+
−
 
+
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    template<> class numeric_limits<bool>;
+
−
 
+
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    template<> class numeric_limits<char>;
+
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    template<> class numeric_limits<signed char>;
+
−
    template<> class numeric_limits<unsigned char>;
+
−
    template<> class numeric_limits<char16_t>;
+
−
    template<> class numeric_limits<char32_t>;
+
−
    template<> class numeric_limits<wchar_t>;
+
−
 
+
−
    template<> class numeric_limits<short>;
+
−
    template<> class numeric_limits<int>;
+
−
    template<> class numeric_limits<long>;
+
−
    template<> class numeric_limits<long long>;
+
−
    template<> class numeric_limits<unsigned short>;
+
−
    template<> class numeric_limits<unsigned int>;
+
−
    template<> class numeric_limits<unsigned long>;
+
−
    template<> class numeric_limits<unsigned long long>;
+
−
 
+
−
    template<> class numeric_limits<float>;
+
−
    template<> class numeric_limits<double>;
+
−
    template<> class numeric_limits<long double>;
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−
}
+
−
 
+
−
}}
+
−
 
+
−
 
+
−
====Class template {{lc|std::numeric_limits}}====
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−
{{source|
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template<class T> class numeric_limits {
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public:
+
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    static constexpr bool is_specialized {{=}} false;
+
−
 
+
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    static constexpr T min() noexcept { return T(); }
+
−
    static constexpr T max() noexcept { return T(); }
+
−
    static constexpr T lowest() noexcept { return T(); }
+
−
 
+
−
    static constexpr int digits {{=}} 0;
+
−
    static constexpr int digits10 {{=}} 0;
+
−
    static constexpr int max_digits10 {{=}} 0;
+
−
 
+
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    static constexpr bool is_signed {{=}} false;
+
−
    static constexpr bool is_integer {{=}} false;
+
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    static constexpr bool is_exact {{=}} false;
+
−
    static constexpr int radix {{=}} 0;
+
−
    static constexpr T epsilon() noexcept { return T(); }
+
−
    static constexpr T round_error() noexcept { return T(); }
+
−
 
+
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    static constexpr int min_exponent {{=}} 0;
+
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    static constexpr int min_exponent10 {{=}} 0;
+
−
    static constexpr int max_exponent {{=}} 0;
+
−
    static constexpr int max_exponent10 {{=}} 0;
+
−
 
+
−
    static constexpr bool has_infinity {{=}} false;
+
−
    static constexpr bool has_quiet_NaN {{=}} false;
+
−
    static constexpr bool has_signaling_NaN {{=}} false;
+
−
    static constexpr float_denorm_style has_denorm {{=}} denorm_absent;
+
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    static constexpr bool has_denorm_loss {{=}} false;
+
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    static constexpr T infinity() noexcept { return T(); }
+
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    static constexpr T quiet_NaN() noexcept { return T(); }
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    static constexpr T signaling_NaN() noexcept { return T(); }
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    static constexpr T denorm_min() noexcept { return T(); }
+
−
 
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    static constexpr bool is_iec559 {{=}} false;
+
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    static constexpr bool is_bounded {{=}} false;
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    static constexpr bool is_modulo {{=}} false;
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−
 
+
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    static constexpr bool traps {{=}} false;
+
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    static constexpr bool tinyness_before {{=}} false;
+
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    static constexpr float_round_style round_style {{=}} round_toward_zero;
+
−
 
+
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};
+
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}}
+
−
 
+
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====Specialization {{c|std::numeric_limits<bool>}}====
+
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{{source|
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template<> class numeric_limits<bool> {
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public:
+
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    static constexpr bool is_specialized {{=}} true;
+
−
 
+
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    static constexpr bool min() noexcept { return false; }
+
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    static constexpr bool max() noexcept { return true; }
+
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    static constexpr bool lowest() noexcept { return false; }
+
−
 
+
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    static constexpr int digits {{=}} 1;
+
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    static constexpr int digits10 {{=}} 0;
+
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    static constexpr int max_digits10 {{=}} 0;
+
−
   
+
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    static constexpr bool is_signed {{=}} false;
+
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    static constexpr bool is_integer {{=}} true;
+
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    static constexpr bool is_exact {{=}} true;
+
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    static constexpr int radix {{=}} 2;
+
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    static constexpr bool epsilon() noexcept { return 0; }
+
−
    static constexpr bool round_error() noexcept { return 0; }
+
−
 
+
−
    static constexpr int min_exponent {{=}} 0;
+
−
    static constexpr int min_exponent10 {{=}} 0;
+
−
    static constexpr int max_exponent {{=}} 0;
+
−
    static constexpr int max_exponent10 {{=}} 0;
+
−
 
+
−
    static constexpr bool has_infinity {{=}} false;
+
−
    static constexpr bool has_quiet_NaN {{=}} false;
+
−
    static constexpr bool has_signaling_NaN {{=}} false;
+
−
    static constexpr float_denorm_style has_denorm {{=}} denorm_absent;
+
−
    static constexpr bool has_denorm_loss {{=}} false;
+
−
    static constexpr bool infinity() noexcept { return 0; }
+
−
    static constexpr bool quiet_NaN() noexcept { return 0; }
+
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    static constexpr bool signaling_NaN() noexcept { return 0; }
+
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    static constexpr bool denorm_min() noexcept { return 0; }
+
−
 
+
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    static constexpr bool is_iec559 {{=}} false;
+
−
    static constexpr bool is_bounded {{=}} true;
+
−
    static constexpr bool is_modulo {{=}} false;
+
−
 
+
−
    static constexpr bool traps {{=}} false;
+
−
    static constexpr bool tinyness_before {{=}} false;
+
−
    static constexpr float_round_style round_style {{=}} round_toward_zero;
+
−
 
+
−
};
+
−
}}
+

Latest revision as of 03:45, 29 November 2023

 
C++
 
Standard library headers
 

This header is part of the type support library.

Contents

[edit] Declarations

 provides an interface to query properties of all fundamental numeric types
(class template) [edit]
indicates floating-point rounding modes
(enum) [edit]
indicates floating-point denormalization modes
(enum) [edit]

[edit] Synopsis

namespace std {
    enum float_round_style;
    enum float_denorm_style;
 
    template<class T> class numeric_limits;
 
    template<class T> class numeric_limits<const T>;
    template<class T> class numeric_limits<volatile T>;
    template<class T> class numeric_limits<const volatile T>;
 
    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<char8_t>;
    template<> class numeric_limits<char16_t>;
    template<> class numeric_limits<char32_t>;
    template<> class numeric_limits<wchar_t>;
 
    template<> class numeric_limits<short>;
    template<> class numeric_limits<int>;
    template<> class numeric_limits<long>;
    template<> class numeric_limits<long long>;
    template<> class numeric_limits<unsigned short>;
    template<> class numeric_limits<unsigned int>;
    template<> class numeric_limits<unsigned long>;
    template<> class numeric_limits<unsigned long long>;
 
    template<> class numeric_limits<float>;
    template<> class numeric_limits<double>;
    template<> class numeric_limits<long double>;
}

[edit] Enumeration std::float_round_style

namespace std {
    enum float_round_style {
        round_indeterminate       = -1,
        round_toward_zero         =  0,
        round_to_nearest          =  1,
        round_toward_infinity     =  2,
        round_toward_neg_infinity =  3,
    };
}

[edit] Enumeration std::float_denorm_style

namespace std {
    enum float_denorm_style {
        denorm_indeterminate = -1,
        denorm_absent        =  0,
        denorm_present       =  1
    };
}

[edit] Class template std::numeric_limits

template<class T> class numeric_limits {
public:
    static constexpr bool is_specialized = false;
 
    static constexpr T min() noexcept { return T(); }
    static constexpr T max() noexcept { return T(); }
    static constexpr T lowest() noexcept { return T(); }
 
    static constexpr int digits = 0;
    static constexpr int digits10 = 0;
    static constexpr int max_digits10 = 0;
 
    static constexpr bool is_signed = false;
    static constexpr bool is_integer = false;
    static constexpr bool is_exact = false;
    static constexpr int radix = 0;
    static constexpr T epsilon() noexcept { return T(); }
    static constexpr T round_error() noexcept { return T(); }
 
    static constexpr int min_exponent = 0;
    static constexpr int min_exponent10 = 0;
    static constexpr int max_exponent = 0;
    static constexpr int max_exponent10 = 0;
 
    static constexpr bool has_infinity = false;
    static constexpr bool has_quiet_NaN = false;
    static constexpr bool has_signaling_NaN = false;
    static constexpr float_denorm_style has_denorm = denorm_absent;
    static constexpr bool has_denorm_loss = false;
    static constexpr T infinity() noexcept { return T(); }
    static constexpr T quiet_NaN() noexcept { return T(); }
    static constexpr T signaling_NaN() noexcept { return T(); }
    static constexpr T denorm_min() noexcept { return T(); }
 
    static constexpr bool is_iec559 = false;
    static constexpr bool is_bounded = false;
    static constexpr bool is_modulo = false;
 
    static constexpr bool traps = false;
    static constexpr bool tinyness_before = false;
    static constexpr float_round_style round_style = round_toward_zero;
};

[edit] Specialization std::numeric_limits<bool>

template<> class numeric_limits<bool> {
public:
    static constexpr bool is_specialized = true;
 
    static constexpr bool min() noexcept { return false; }
    static constexpr bool max() noexcept { return true; }
    static constexpr bool lowest() noexcept { return false; }
 
    static constexpr int digits = 1;
    static constexpr int digits10 = 0;
    static constexpr int max_digits10 = 0;
 
    static constexpr bool is_signed = false;
    static constexpr bool is_integer = true;
    static constexpr bool is_exact = true;
    static constexpr int radix = 2;
    static constexpr bool epsilon() noexcept { return 0; }
    static constexpr bool round_error() noexcept { return 0; }
 
    static constexpr int min_exponent = 0;
    static constexpr int min_exponent10 = 0;
    static constexpr int max_exponent = 0;
    static constexpr int max_exponent10 = 0;
 
    static constexpr bool has_infinity = false;
    static constexpr bool has_quiet_NaN = false;
    static constexpr bool has_signaling_NaN = false;
    static constexpr float_denorm_style has_denorm = denorm_absent;
    static constexpr bool has_denorm_loss = false;
    static constexpr bool infinity() noexcept { return 0; }
    static constexpr bool quiet_NaN() noexcept { return 0; }
    static constexpr bool signaling_NaN() noexcept { return 0; }
    static constexpr bool denorm_min() noexcept { return 0; }
 
    static constexpr bool is_iec559 = false;
    static constexpr bool is_bounded = true;
    static constexpr bool is_modulo = false;
 
    static constexpr bool traps = false;
    static constexpr bool tinyness_before = false;
    static constexpr float_round_style round_style = round_toward_zero;
};

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 184 C++98 the definition of the specialization std::numeric_limits<bool> was not provided provided
LWG 559 C++98 the std::numeric_limits specializations of cv-qualified
arithmetic types were missing in the synopsis 		added
Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/header/limits&oldid=164373"