FE_DIVBYZERO, FE_INEXACT, FE_INVALID, FE_OVERFLOW, FE_UNDERFLOW, FE_ALL_EXCEPT
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Macro constants
FE_ALL_EXCEPTFE_DIVBYZEROFE_INEXACTFE_INVALIDFE_OVERFLOWFE_UNDERFLOW
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(C++11)(C++11)(C++11)(C++11)
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Defined in header
<cfenv>
#define FE_DIVBYZERO /*implementation defined power of 2*/
(since C++11)
#define FE_INEXACT /*implementation defined power of 2*/
(since C++11)
#define FE_INVALID /*implementation defined power of 2*/
(since C++11)
#define FE_OVERFLOW /*implementation defined power of 2*/
(since C++11)
#define FE_UNDERFLOW /*implementation defined power of 2*/
(since C++11)
#define FE_ALL_EXCEPT FE_DIVBYZERO | FE_INEXACT | \
(since C++11)
FE_INVALID | FE_OVERFLOW | \
All these macro constants (except FE_ALL_EXCEPT) expand to integer constant expressions that are distinct powers of 2, which uniquely identify all supported floating-point exceptions. Each macro is defined only if it is supported.
The macro constant FE_ALL_EXCEPT, which expands to the bitwise OR of all other FE_*, is always defined and is zero if floating-point exceptions are not supported by the implementation.
Constant
Explanation
FE_DIVBYZERO
pole error occurred in an earlier floating-point operation
FE_INEXACT
inexact result: rounding was necessary to store the result of an earlier floating-point operation
FE_INVALID
domain error occurred in an earlier floating-point operation
FE_OVERFLOW
the result of the earlier floating-point operation was too large to be representable
FE_UNDERFLOW
the result of the earlier floating-point operation was subnormal with a loss of precision
FE_ALL_EXCEPT
bitwise OR of all supported floating-point exceptions
The implementation may define additional macro constants in <cfenv> to identify additional floating-point exceptions. All such constants begin with FE_ followed by at least one uppercase letter.
See math_errhandling for further details.
[edit] Example
Run this code
#include <cfenv> #include <cmath> #include <iostream> // #pragma STDC FENV_ACCESS ON volatile double zero = 0.0; // volatile not needed where FENV_ACCESS is supported volatile double one = 1.0; // volatile not needed where FENV_ACCESS is supported int main() { std::feclearexcept (FE_ALL_EXCEPT); std::cout << "1.0/0.0 = " << 1.0 / zero << '\n'; if (std::fetestexcept (FE_DIVBYZERO)) std::cout << "division by zero reported\n"; else std::cout << "division by zero not reported\n"; std::feclearexcept (FE_ALL_EXCEPT); std::cout << "1.0/10 = " << one / 10 << '\n'; if (std::fetestexcept (FE_INEXACT)) std::cout << "inexact result reported\n"; else std::cout << "inexact result not reported\n"; std::feclearexcept (FE_ALL_EXCEPT); std::cout << "sqrt(-1) = " << std::sqrt (-1) << '\n'; if (std::fetestexcept (FE_INVALID)) std::cout << "invalid result reported\n"; else std::cout << "invalid result not reported\n"; }
Possible output:
1.0/0.0 = inf division by zero reported 1.0/10 = 0.1 inexact result reported sqrt(-1) = -nan invalid result reported
[edit] See also
(C++11)(C++11)(C++11)
(macro constant) [edit]
C documentation for floating point exception macros