std::numeric_limits<T>::min_exponent

 

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static const int min_exponent;		(until C++11)
static constexpr int min_exponent;		(since C++11)

The value of std::numeric_limits<T>::min_exponent is the lowest negative number n such that \(\scriptsize r^{n-1}\)rn-1
, where r is std::numeric_limits<T>::radix, is a valid normalized value of the floating-point type T.

Standard specializations

T	value of std::numeric_limits<T>::min_exponent
/* non-specialized */	​0​
bool	​0​
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 C++11)	​0​
float	FLT_MIN_EXP
double	DBL_MIN_EXP
long double	LDBL_MIN_EXP

Example

Demonstrates the relationships of min_exponent, min_exponent10, min(), and radix for the type float:

Run this code

#include <iostream>
#include <limits>
 
int main()
{
    std::cout << "min() = " << std::numeric_limits<float>::min() << '\n'
              << "min_exponent10 = " << std::numeric_limits<float>::min_exponent10 << '\n'
              << std::hexfloat << '\n'
              << "min() = " << std::numeric_limits<float>::min() << '\n'
              << "min_exponent = " << std::numeric_limits<float>::min_exponent << '\n';
}

Output:

min() = 1.17549e-38
min_exponent10 = -37
 
min() = 0x1p-126
min_exponent = -125

See also

radix [static]	the radix or integer base used by the representation of the given type (public static member constant)
min_exponent10 [static]	the smallest negative power of ten that is a valid normalized floating-point value (public static member constant)
max_exponent [static]	one more than the largest integer power of the radix that is a valid finite floating-point value (public static member constant)
max_exponent10 [static]	the largest integer power of 10 that is a valid finite floating-point value (public static member constant)