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Standard library header <cfenv> (C++11)

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Standard library headers

This header was originally in the C standard library as <fenv.h> .

This header is part of the floating-point environment library.

Contents

Types

fenv_t
(C++11)
the type representing the entire floating-point environment
(typedef)
fexcept_t
(C++11)
the type representing all floating-point status flags collectively
(typedef)

Functions

(C++11)
clears the specified floating-point status flags
(function)
(C++11)
determines which of the specified floating-point status flags are set
(function)
(C++11)
raises the specified floating-point exceptions
(function)
(C++11) (C++11)
copies the state of the specified floating-point status flags from or to the floating-point environment
(function)
(C++11) (C++11)
gets or sets rounding direction
(function)
(C++11)
saves or restores the current floating-point environment
(function)
(C++11)
saves the environment, clears all status flags and ignores all future errors
(function)
(C++11)
restores the floating-point environment and raises the previously raised exceptions
(function)

Macros

(C++11)
floating-point exceptions
(macro constant)
(C++11)
floating-point rounding direction
(macro constant)
(C++11)
default floating-point environment
(macro constant)

Synopsis 

#define FE_ALL_EXCEPT /* see description */
#define FE_DIVBYZERO /* see description */    // optional
#define FE_INEXACT /* see description */      // optional
#define FE_INVALID /* see description */      // optional
#define FE_OVERFLOW /* see description */     // optional
#define FE_UNDERFLOW /* see description */    // optional
#define FE_DOWNWARD /* see description */     // optional
#define FE_TONEAREST /* see description */    // optional
#define FE_TOWARDZERO /* see description */   // optional
#define FE_UPWARD /* see description */       // optional
#define FE_DFL_ENV /* see description */
namespace std {
    // types
    using fenv_t    = /* object type */;
    using fexcept_t = /* object type */;
    // functions
    int feclearexcept(int except);
    int fegetexceptflag(fexcept_t* pflag, int except);
    int feraiseexcept(int except);
    int fesetexceptflag(const fexcept_t* pflag, int except);
    int fetestexcept(int except);
    int fegetround(void);
    int fesetround(int mode);
    int fegetenv(fenv_t* penv);
    int feholdexcept(fenv_t* penv);
    int fesetenv(const fenv_t* penv);
    int feupdateenv(const fenv_t* penv);
}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3905 C++11 std::fexcept_t must be an integer type it is an object type