std::numeric_limits<T>::denorm_min
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 (C++20) |
0 |
char16_t (C++11) |
0 |
char32_t (C++11) |
0 |
short |
0 |
unsigned short |
0 |
int |
0 |
unsigned int |
0 |
long |
0 |
unsigned long |
0 |
long long (C++11) |
0 |
unsigned long long (C++11) |
0 |
float |
FLT_TRUE_MIN (\(\scriptsize 2^{-149}\)2-149if std::numeric_limits<float>::is_iec559 is true ) |
double |
DBL_TRUE_MIN (\(\scriptsize 2^{-1074}\)2-1074if 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.
#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 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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