std::numeric_limits::digits10

 

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numeric_limits::digits10

numeric_limits::max_digits10 (C++11)

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numeric_limits::min_exponent10

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numeric_limits::max_exponent10

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static const int digits10;		(until C++11)
static constexpr int digits10		(since C++11)

The value of std::numeric_limits<T>::digits10 is the number of base-10 digits that can be represented by the type T without change, that is, any number with this many decimal digits can be converted to a value of type T and back to decimal form, without change due to rounding or overflow. For base-radix types, it is the value of digits (digits-1 for floating-point types) multiplied by log
10(radix) and rounded down.

Standard specializations

T	value of std::numeric_limits<T>::digits10
/* non-specialized */	​0​
bool	​0​
char	std::numeric_limits<char>::digits * std::log10(2)
signed char	std::numeric_limits<signed char>::digits * std::log10(2)
unsigned char	std::numeric_limits<unsigned char>::digits * std::log10(2)
wchar_t	std::numeric_limits<wchar_t>::digits * std::log10(2)
char16_t	std::numeric_limits<char16_t>::digits * std::log10(2)
char32_t	std::numeric_limits<char32_t>::digits * std::log10(2)
short	std::numeric_limits<short>::digits * std::log10(2)
unsigned short	std::numeric_limits<unsigned short>::digits * std::log10(2)
int	std::numeric_limits<int>::digits * std::log10(2)
unsigned int	std::numeric_limits<unsigned int>::digits * std::log10(2)
long	std::numeric_limits<long>::digits * std::log10(2)
unsigned long	std::numeric_limits<unsigned long>::digits * std::log10(2)
long long	std::numeric_limits<long long>::digits * std::log10(2)
unsigned long long	std::numeric_limits<unsigned long long>::digits * std::log10(2)
float	FLT_DIG
double	DBL_DIG
long double	LDBL_DIG