std::numeric_limits::denorm_min(3)

NAME
std::numeric_limits::denorm_min - std::numeric_limits::denorm_min

Synopsis
   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 (\(\scriptsize 2^{-149}\)2-149
                        if std::numeric_limits<float>::is_iec559 is true)
   double DBL_TRUE_MIN (\(\scriptsize 2^{-1074}\)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
   min returns the smallest finite value of the given type
   [static] (public static member function)
   has_denorm identifies the denormalization style used by the floating-point
   [static] type
                    (public static member constant)
   lowest returns the lowest finite value of the given type
   [static] (C++11) (public static member function)