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numeric_limits::denorm_min | ||||
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static T denorm_min()throw(); | (until C++11) | |
staticconstexpr T denorm_min()noexcept; | (since C++11) | |
Returns the minimum positivesubnormal value of the typeT, ifstd::numeric_limits<T>::has_denorm!=std::denorm_absent, otherwise returnsstd::numeric_limits<T>::min() for floating point types andT() for all other types. Only meaningful for floating-point types.
T | std::numeric_limits<T>::denorm_min() |
| /* non-specialized */ | T() |
| bool | false |
| char | 0 |
| signedchar | 0 |
| unsignedchar | 0 |
| wchar_t | 0 |
| char8_t(since C++20) | 0 |
| char16_t(since C++11) | 0 |
| char32_t(since C++11) | 0 |
| short | 0 |
| unsignedshort | 0 |
| int | 0 |
| unsignedint | 0 |
| long | 0 |
| unsignedlong | 0 |
| longlong(since C++11) | 0 |
| unsignedlonglong since(since C++11) | 0 |
| float | FLT_TRUE_MIN (\(\scriptsize 2^{-149}\)2-149 if std::numeric_limits<float>::is_iec559 istrue) |
| double | DBL_TRUE_MIN (\(\scriptsize 2^{-1074}\)2-1074 if std::numeric_limits<double>::is_iec559 istrue) |
| longdouble | LDBL_TRUE_MIN |
Demonstates the underlying bit structure of thedenorm_min() and prints the values:
#include <cassert>#include <cstdint>#include <cstring>#include <iostream>#include <limits> int main(){// the smallest subnormal value has sign bit = 0, exponent = 0// and only the least significant bit of the fraction is 1std::uint32_t denorm_bits=0x0001;float denorm_float;std::memcpy(&denorm_float,&denorm_bits, sizeof(float)); assert(denorm_float==std::numeric_limits<float>::denorm_min()); std::cout<<"float\tmin()\t\tdenorm_min()\n";std::cout<<"\t"<<std::numeric_limits<float>::min()<<'\t';std::cout<<std::numeric_limits<float>::denorm_min()<<'\n'; std::cout<<"double\tmin()\t\tdenorm_min()\n";std::cout<<"\t"<<std::numeric_limits<double>::min()<<'\t';std::cout<<std::numeric_limits<double>::denorm_min()<<'\n';}
Possible output:
floatmin()denorm_min()1.17549e-381.4013e-45doublemin()denorm_min()2.22507e-3084.94066e-324
[static] | returns the smallest finite value of the given non-floating-point type, or the smallest positive normal value of the given floating-point type (public static member function)[edit] |
[static] | identifies the denormalization style used by the floating-point type (public static member constant)[edit] |
[static](C++11) | returns the lowest finite value of the given type, i.e. the most negative value for signed types,0 for unsigned types (public static member function)[edit] |
