static T denorm_min() throw(); | (until C++11) | |
static constexpr T denorm_min() noexcept; | (since C++11) |
Returns the minimum positive subnormal value of the type T, if std::numeric_limits<T>::has_denorm != std::denorm_absent, otherwise returns std::numeric_limits<T>::min(). Only meaningful for floating-point types.
T | std::numeric_limits<T>::denorm_min() |
|---|---|
| /* non-specialized */ | T() |
bool | false |
char | 0 |
signed char | 0 |
unsigned char | 0 |
wchar_t | 0 |
char8_t | 0 |
char16_t | 0 |
char32_t | 0 |
short | 0 |
unsigned short | 0 |
int | 0 |
unsigned int | 0 |
long | 0 |
unsigned long | 0 |
long long | 0 |
unsigned long long | 0 |
float | 2-149 if std::numeric_limits<float>::is_iec559 == true |
double | 2-1074 if std::numeric_limits<double>::is_iec559 == true |
long double | /* implementation-defined */ |
Demonstates the underlying bit structure of the denorm_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 1
std::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:
float min() denorm_min()
1.17549e-38 1.4013e-45
double min() denorm_min()
2.22507e-308 4.94066e-324|
[static] | returns the smallest finite value of the given type (public static member function) |
|
[static] | identifies the denormalization style used by the floating-point type (public static member constant) |
|
[static] (C++11) | returns the lowest finite value of the given type (public static member function) |
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