std::numeric_limits

`<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<signed char>; template<> class numeric_limits<unsigned char>; 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<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>;

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.

Template parameters

T

-

a type to retrieve numeric properties for

Member constants

is_specialized [static]	identifies types for which std::numeric_limits is specialized (public static member constant) [edit]
is_signed [static]	identifies signed types (public static member constant) [edit]
is_integer [static]	identifies integer types (public static member constant) [edit]
is_exact [static]	identifies exact types (public static member constant) [edit]
has_infinity [static]	identifies floating-point types that can represent the special value "positive infinity" (public static member constant) [edit]
has_quiet_NaN [static]	identifies floating-point types that can represent the special value "quiet not-a-number" (NaN) (public static member constant) [edit]
has_signaling_NaN [static]	identifies floating-point types that can represent the special value "signaling not-a-number" (NaN) (public static member constant) [edit]
has_denorm [static]	identifies the denormalization style used by the floating-point type (public static member constant) [edit]
has_denorm_loss [static]	identifies the floating-point types that detect loss of precision as denormalization loss rather than inexact result (public static member constant) [edit]
round_style [static]	identifies the rounding style used by the type (public static member constant) [edit]
is_iec559 [static]	identifies the IEC 559/IEEE 754 floating-point types (public static member constant) [edit]
is_bounded [static]	identifies types that represent a finite set of values (public static member constant) [edit]
is_modulo [static]	identifies types that handle overflows with modulo arithmetic (public static member constant) [edit]
digits [static]	number of `radix` digits that can be represented without change (public static member constant) [edit]
digits10 [static]	number of decimal digits that can be represented without change (public static member constant) [edit]
max_digits10 [static] (C++11)	number of decimal digits necessary to differentiate all values of this type (public static member constant) [edit]
radix [static]	the radix or integer base used by the representation of the given type (public static member constant) [edit]
min_exponent [static]	one more than the smallest negative power of the radix that is a valid normalized floating-point value (public static member constant) [edit]
min_exponent10 [static]	the smallest negative power of ten that is a valid normalized floating-point value (public static member constant) [edit]
max_exponent [static]	one more than the largest integer power of the radix that is a valid finite floating-point value (public static member constant) [edit]
max_exponent10 [static]	the largest integer power of 10 that is a valid finite floating-point value (public static member constant) [edit]
traps [static]	identifies types which can cause arithmetic operations to trap (public static member constant) [edit]
tinyness_before [static]	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) [edit]
lowest [static] (C++11)	returns the lowest finite value of the given type (public static member function) [edit]
max [static]	returns the largest finite value of the given type (public static member function) [edit]
epsilon [static]	returns the difference between `1.0` and the next representable value of the given floating-point type (public static member function) [edit]
round_error [static]	returns the maximum rounding error of the given floating-point type (public static member function) [edit]
infinity [static]	returns the positive infinity value of the given floating-point type (public static member function) [edit]
quiet_NaN [static]	returns a quiet NaN value of the given floating-point type (public static member function) [edit]
signaling_NaN [static]	returns a signaling NaN value of the given floating-point type (public static member function) [edit]
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 (enum) [edit]
float_denorm_style	indicates floating-point denormalization modes (enum) [edit]

Relationship with C library macro constants

Specialization	Members
Specialization	`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_>`	SHRT_MIN	SHRT_MIN	SHRT_MAX								`2`
`_{numeric_limits<}unsigned short_>`	`0`	`0`	USHRT_MAX								`2`
`_{numeric_limits<}int_>`	INT_MIN	INT_MIN	INT_MAX								`2`
`_{numeric_limits<}signed int_>`	INT_MIN	INT_MIN	INT_MAX								`2`
`_{numeric_limits<}unsigned int_>`	`0`	`0`	UINT_MAX								`2`
`_{numeric_limits<}long_>`	LONG_MIN	LONG_MIN	LONG_MAX								`2`
`_{numeric_limits<}signed long_>`	LONG_MIN	LONG_MIN	LONG_MAX								`2`
`_{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_>`	LLONG_MIN	LLONG_MIN	LLONG_MAX								`2`
`_{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

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

컴파일러 지원
Freestanding and hosted
언어
표준 라이브러리 헤더
명명된 요구사항
Feature test macros (C++20)
언어 지원 라이브러리
개념 (C++20)
Diagnostics library
유틸리티 라이브러리
문자열 라이브러리
컨테이너 라이브러리
반복자 라이브러리
범위 라이브러리 (C++20)
알고리즘 라이브러리
수치 라이브러리
지역화 라이브러리
입/출력 라이브러리
파일시스템 라이브러리 (C++17)
정규 표현식 라이브러리 (C++11)
아토믹 연산 라이브러리 (C++11)
쓰레드 지원 라이브러리 (C++11)
Technical specifications
Symbols index
외부 라이브러리들

컴파일러 지원
Freestanding and hosted
언어
표준 라이브러리 헤더
Named requirements
기능 검사 매크로 (C++20)
언어 지원 라이브러리
Concepts 라이브러리 (C++20)
Diagnostics 라이브러리
일반 도구 라이브러리
문자열 라이브러리
컨테이너 라이브러리
반복자 라이브러리
Ranges 라이브러리 (C++20)
알고리즘 라이브러리
수치 알고리즘
지역화 라이브러리
입/출력 라이브러리
파일시스템 라이브러리 (C++17)
정규표현식 라이브러리 (C++11)
아토믹 연산 라이브러리 (C++11)
쓰레드 지원 라이브러리 (C++11)
기술적 표준
Symbols index
외부 라이브러리

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

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