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      std::numeric_limits

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      std::numeric_limits
      Static constants
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      Static member functions
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      <limits> 에 정의되어 있음.
      template<class T >class numeric_limits;

      numeric_limits 클래스 템플릿은 산술형의 다양한 속성을 조회할 수 있는 표준화된 방법을 제공한다. (예컨데 int형이 가질 수 있는 최댓값은 std::numeric_limits<int>::max()이다).

      이 정보는 numeric_limits 템플릿의 특수화를 통해 얻어진다. 표준 라이브러리는 모든 산술형에 대한 특수화를 제공한다.:

      <limits> 에 정의되어 있음.
      template<>class numeric_limits<bool>;

      template<>class numeric_limits<char>;
      template<>class numeric_limits<signedchar>;
      template<>class numeric_limits<unsignedchar>;
      template<>class numeric_limits<wchar_t>;
      template<>class numeric_limits<char16_t>;   // C++11 기능
      template<>class numeric_limits<char32_t>;   // C++11 기능
      template<>class numeric_limits<short>;
      template<>class numeric_limits<unsignedshort>;
      template<>class numeric_limits<int>;
      template<>class numeric_limits<unsignedint>;
      template<>class numeric_limits<long>;
      template<>class numeric_limits<unsignedlong>;
      template<>class numeric_limits<longlong>;
      template<>class numeric_limits<unsignedlonglong>;
      template<>class numeric_limits<float>;
      template<>class numeric_limits<double>;

      template<>class numeric_limits<longdouble>;

      Additionally, a specialization exists for every cv-qualified version of each arithmetic type, identical to the unqualified specialization, e.g. std::numeric_limits<const int>, std::numeric_limits<volatile int>, and std::numeric_limits<const volatile int> are provided and are equivalent to std::numeric_limits<int>.

      The standard library types that are 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.

      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.

      목차

      [편집]Template parameters

      T - a type to retrieve numeric properties for

      [편집]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)[edit]
      [static]
      		 the largest integer power of 10 that is a valid finite floating-point value
      (public static member constant)[edit]
      [static]
      		 identifies types which can cause arithmetic operations to trap
      (public static member constant)[edit]
      [static]
      		 identifies floating-point types that detect tinyness before rounding
      (public static member constant)[edit]

      [편집]Member functions

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

      [편집]Helper classes

      		 indicates floating-point rounding modes
      (enum)[edit]
      		 indicates floating-point denormalization modes
      (enum)[edit]

      [편집]Relationship with C library macro constants

      Specialization Members
      min()lowest()
      (C++11)      		max()epsilon()digitsdigits10min_exponentmin_exponent10max_exponentmax_exponent10radix
      numeric_limits< bool >2
      numeric_limits< char >CHAR_MINCHAR_MINCHAR_MAX2
      numeric_limits< signedchar >SCHAR_MINSCHAR_MINSCHAR_MAX2
      numeric_limits< unsignedchar >​0​​0​UCHAR_MAX2
      numeric_limits< wchar_t >WCHAR_MINWCHAR_MINWCHAR_MAX2
      numeric_limits< char16_t >​0​​0​UINT_LEAST16_MAX2
      numeric_limits< char32_t >​0​​0​UINT_LEAST32_MAX2
      numeric_limits< short >SHRT_MINSHRT_MINSHRT_MAX2
      numeric_limits< signedshort >
      numeric_limits< unsignedshort >​0​​0​USHRT_MAX2
      numeric_limits< int >INT_MININT_MININT_MAX2
      numeric_limits< signedint >
      numeric_limits< unsignedint >​0​​0​UINT_MAX2
      numeric_limits< long >LONG_MINLONG_MINLONG_MAX2
      numeric_limits< signedlong >
      numeric_limits< unsignedlong >​0​​0​ULONG_MAX2
      numeric_limits< longlong >LLONG_MINLLONG_MINLLONG_MAX2
      numeric_limits< signedlonglong >
      numeric_limits< unsignedlonglong >​0​​0​ULLONG_MAX2
      numeric_limits< float >FLT_MIN-FLT_MAXFLT_MAXFLT_EPSILONFLT_MANT_DIGFLT_DIGFLT_MIN_EXPFLT_MIN_10_EXPFLT_MAX_EXPFLT_MAX_10_EXPFLT_RADIX
      numeric_limits< double >DBL_MIN-DBL_MAXDBL_MAXDBL_EPSILONDBL_MANT_DIGDBL_DIGDBL_MIN_EXPDBL_MIN_10_EXPDBL_MAX_EXPDBL_MAX_10_EXPFLT_RADIX
      numeric_limits< longdouble >LDBL_MIN-LDBL_MAXLDBL_MAXLDBL_EPSILONLDBL_MANT_DIGLDBL_DIGLDBL_MIN_EXPLDBL_MIN_10_EXPLDBL_MAX_EXPLDBL_MAX_10_EXPFLT_RADIX

      [편집]Example

      코드 실행 
      #include <limits>#include <iostream>   int main(){std::cout<<"type\tlowest\thighest\n";std::cout<<"int\t"<< std::numeric_limits<int>::lowest()<<'\t'<< std::numeric_limits<int>::max()<<'\n';std::cout<<"float\t"<< std::numeric_limits<float>::lowest()<<'\t'<< std::numeric_limits<float>::max()<<'\n';std::cout<<"double\t"<< std::numeric_limits<double>::lowest()<<'\t'<< std::numeric_limits<double>::max()<<'\n';}

      Possible output: 

      type lowest highest int -2147483648 2147483647 float -3.40282e+38 3.40282e+38 double -1.79769e+308 1.79769e+308

      [편집]See also

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