HUGE_VALF, HUGE_VAL, HUGE_VALL

Defined in header <cmath>
#define HUGE_VALF /* implementation defined */		(since C++11)
#define HUGE_VAL  /* implementation defined */
#define HUGE_VALL /* implementation defined */		(since C++11)

The macros HUGE_VALF, HUGE_VAL and HUGE_VALL macros expand to positive floating point constant expressions which compare equal to the values returned by floating-point functions and operators in case of overflow (see math_errhandling

Constant	Explanation
HUGE_VALF	Expands to positive float expression that indicates overflow
HUGE_VAL	Expands to positive double expression that indicates overflow, not necessarily representable as a float
HUGE_VALL	Expands to positive long double expression that indicates overflow, not necessarily representable as a float or double

On implementations that support floating-point infinities, these macros always expand to the positive infinities of float, double, and long double

Notes

On implementations that do not support floating-point infinities, these macros expand to the maximum finite number of their respective types.

C++98 added float and long double overloads of mathematical functions. There is a problem that the float overloads cannot return HUGE_VAL to indicate overflow because this macro is not guaranteed to be representable as a float

LWG issue 357 was raised to target this problem. LWG found that C99 has the same problem (float and long double overloads were also added in C99), and C99 introduced new macros HUGE_VALF and HUGE_VALL

See also

INFINITY (C++11)	evaluates to positive infinity or the value guaranteed to overflow a float (macro constant)
C documentation for HUGE_VAL