std::numeric_limits<T>::traps

 

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C numeric limits interface
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numeric_limits::is_specialized

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numeric_limits::signaling_NaN

numeric_limits::denorm_min

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float_denorm_style

 

static const bool traps;		(until C++11)
static constexpr bool traps;		(since C++11)

The value of std::numeric_limits<T>::traps is true for all arithmetic types T that have at least one value that, if used as an argument to an arithmetic operation, will generate a trap.

Standard specializations

T	value of std::numeric_limits<T>::traps
/* non-specialized */	false
bool	false
char	usually true
signed char	usually true
unsigned char	usually true
wchar_t	usually true
char8_t (C++20)	usually true
char16_t (C++11)	usually true
char32_t (C++11)	usually true
short	usually true
unsigned short	usually true
int	usually true
unsigned int	usually true
long	usually true
unsigned long	usually true
long long (C++11)	usually true
unsigned long long (C++11)	usually true
float	usually false
double	usually false
long double	usually false

Notes

On most platforms integer division by zero always traps, and std::numeric_limits<T>::traps is true for all integer types that support the value 0. The exception is the type bool: even though division by false traps due to integral promotion from bool to int, it is the zero-valued int that traps. Zero is not a value of type bool.

On most platforms, floating-point exceptions may be turned on and off at run time (e.g. feenableexcept() on Linux or _controlfp on Windows), in which case the value of std::numeric_limits<T>::traps for floating-point types reflects the state of floating-point trapping facility at the time of program startup, which is false on most modern systems. An exception would be a DEC Alpha program, where it is true if compiled without -ieee.

See also

Floating-point environment
tinyness_before [static]	identifies floating-point types that detect tinyness before rounding (public static member constant)
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)