Which member function returns the largest integer value that is equal to or less than a number?

template class numeric_limits;

The numeric_limits class template provides a standardized way to query various properties of arithmetic types [e.g. the largest possible value for type int is std::numeric_limits::max[]].

This information is provided via specializations of the numeric_limits template. The standard library makes available specializations for all arithmetic types:

Defined in header
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;		[since C++20]
template class numeric_limits;		[since C++11]
template class numeric_limits;		[since C++11]
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;		[since C++11]
template class numeric_limits;		[since C++11]
template class numeric_limits;
template class numeric_limits;
template class numeric_limits;

Additionally, a specialization exists for every cv-qualified version of each cv-unqualified type for which the specialization exists, identical to the unqualified specialization, e.g. std::numeric_limits, std::numeric_limits, and std::numeric_limits are provided and are equivalent to std::numeric_limits.

Aliases of arithmetic types [such as std::size_t or std::streamsize] may also be examined with the std::numeric_limits type traits.

Non-arithmetic standard types, such as std::complex or std::nullptr_t, do not have specializations.

If the implementation defines any integer-class types, specializations of std::numeric_limits must also be provided for them.

[since C++20]

Implementations may provide specializations of std::numeric_limits for implementation-specific types: e.g. GCC provides std::numeric_limits. Non-standard libraries may add specializations for library-provided types, e.g. OpenEXR provides std::numeric_limits for a 16-bit floating-point type.

Contents

• 1 Template parameters
• 2 Member constants
• 3 Member functions
• 4 Helper classes
• 5 Relationship with C library macro constants
• 6 Example
• 7 See also

[edit] Template parameters

T

-

a type to retrieve numeric properties for

[edit] Member constants

is_specialized [static]	identifies types for which std::numeric_limits is specialized [public static member constant] [edit]
is_signed [static]	identifies signed types [public static member constant] [edit]
is_integer [static]	identifies integer types [public static member constant] [edit]
is_exact [static]	identifies exact types [public static member constant] [edit]
has_infinity [static]	identifies floating-point types that can represent the special value "positive infinity" [public static member constant] [edit]
has_quiet_NaN [static]	identifies floating-point types that can represent the special value "quiet not-a-number" [NaN] [public static member constant] [edit]
has_signaling_NaN [static]	identifies floating-point types that can represent the special value "signaling not-a-number" [NaN] [public static member constant] [edit]
has_denorm [static]	identifies the denormalization style used by the floating-point type [public static member constant] [edit]
has_denorm_loss [static]	identifies the floating-point types that detect loss of precision as denormalization loss rather than inexact result [public static member constant] [edit]
round_style [static]	identifies the rounding style used by the type [public static member constant] [edit]
is_iec559 [static]	identifies the IEC 559/IEEE 754 floating-point types [public static member constant] [edit]
is_bounded [static]	identifies types that represent a finite set of values [public static member constant] [edit]
is_modulo [static]	identifies types that handle overflows with modulo arithmetic [public static member constant] [edit]
digits [static]	number of radix digits that can be represented without change [public static member constant] [edit]
digits10 [static]	number of decimal digits that can be represented without change [public static member constant] [edit]
max_digits10 [static] [C++11]	number of decimal digits necessary to differentiate all values of this type [public static member constant] [edit]
radix [static]	the radix or integer base used by the representation of the given type [public static member constant] [edit]
min_exponent [static]	one more than the smallest negative power of the radix that is a valid normalized floating-point value [public static member constant] [edit]
min_exponent10 [static]	the smallest negative power of ten that is a valid normalized floating-point value [public static member constant] [edit]
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] [edit]
max_exponent10 [static]	the largest integer power of 10 that is a valid finite floating-point value [public static member constant] [edit]
traps [static]	identifies types which can cause arithmetic operations to trap [public static member constant] [edit]
tinyness_before [static]	identifies floating-point types that detect tinyness before rounding [public static member constant] [edit]

[edit] Member functions

min [static]	returns the smallest finite value of the given type [public static member function] [edit]
lowest [static] [C++11]	returns the lowest finite value of the given type [public static member function] [edit]
max [static]	returns the largest finite value of the given type [public static member function] [edit]
epsilon [static]	returns the difference between 1.0 and the next representable value of the given floating-point type [public static member function] [edit]
round_error [static]	returns the maximum rounding error of the given floating-point type [public static member function] [edit]
infinity [static]	returns the positive infinity value of the given floating-point type [public static member function] [edit]
quiet_NaN [static]	returns a quiet NaN value of the given floating-point type [public static member function] [edit]
signaling_NaN [static]	returns a signaling NaN value of the given floating-point type [public static member function] [edit]
denorm_min [static]	returns the smallest positive subnormal value of the given floating-point type [public static member function] [edit]

[edit] Helper classes

[edit] Relationship with C library macro constants

Specialization
std::numeric_limits
where T is Members min[] lowest[]
[C++11] max[] radix

bool	false	false	true	2
char	CHAR_MIN	CHAR_MIN	CHAR_MAX	2
signed char	SCHAR_MIN	SCHAR_MIN	SCHAR_MAX	2
unsigned char	​0​	​0​	UCHAR_MAX	2
wchar_t	WCHAR_MIN	WCHAR_MIN	WCHAR_MAX	2
char8_t	​0​	​0​	UCHAR_MAX	2
char16_t	​0​	​0​	UINT_LEAST16_MAX	2
char32_t	​0​	​0​	UINT_LEAST32_MAX	2
short	SHRT_MIN	SHRT_MIN	SHRT_MAX	2
signed short
unsigned short	​0​	​0​	USHRT_MAX	2
int	INT_MIN	INT_MIN	INT_MAX	2
signed int
unsigned int	​0​	​0​	UINT_MAX	2
long	LONG_MIN	LONG_MIN	LONG_MAX	2
signed long
unsigned long	​0​	​0​	ULONG_MAX	2
long long	LLONG_MIN	LLONG_MIN	LLONG_MAX	2
signed long long
unsigned long long	​0​	​0​	ULLONG_MAX	2

Specialization
std::numeric_limits
where T is Members denorm_min[] min[] lowest[]
[C++11] max[] epsilon[] digits digits10

float	FLT_TRUE_MIN	FLT_MIN	-FLT_MAX	FLT_MAX	FLT_EPSILON	FLT_MANT_DIG	FLT_DIG
double	DBL_TRUE_MIN	DBL_MIN	-DBL_MAX	DBL_MAX	DBL_EPSILON	DBL_MANT_DIG	DBL_DIG
long double	LDBL_TRUE_MIN	LDBL_MIN	-LDBL_MAX	LDBL_MAX	LDBL_EPSILON	LDBL_MANT_DIG	LDBL_DIG

Specialization
std::numeric_limits
where T is Members [continue] min_exponent min_exponent10 max_exponent max_exponent10 radix

float	FLT_MIN_EXP	FLT_MIN_10_EXP	FLT_MAX_EXP	FLT_MAX_10_EXP	FLT_RADIX
double	DBL_MIN_EXP	DBL_MIN_10_EXP	DBL_MAX_EXP	DBL_MAX_10_EXP	FLT_RADIX
long double	LDBL_MIN_EXP	LDBL_MIN_10_EXP	LDBL_MAX_EXP	LDBL_MAX_10_EXP	FLT_RADIX

[edit] Example

#include #include   int main[] { std::cout