std::numeric_limits<T>::denorm_min
From cppreference.com
< cpp | types | numeric limits
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() for floating point types and T() for all other types. Only meaningful for floating-point types.
Return value
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 (since C++20) | 0 |
| char16_t (since C++11) | 0 |
| char32_t (since C++11) | 0 |
| short | 0 |
| unsigned short | 0 |
| int | 0 |
| unsigned int | 0 |
| long | 0 |
| unsigned long | 0 |
| long long (since C++11) | 0 |
| unsigned long long since (since C++11) | 0 |
| float | FLT_TRUE_MIN (2-149 if std::numeric_limits<float>::is_iec559 is true) |
| double | DBL_TRUE_MIN (2-1074 if std::numeric_limits<double>::is_iec559 is true) |
| long double | LDBL_TRUE_MIN |
Example
Demonstates the underlying bit structure of the denorm_min() and prints the values:
Run this code
#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
See also
| [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) |
| [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, i.e. the most negative value for signed types, 0 for unsigned types (public static member function) |