< C Programming

fenv.h is a header file containing various functions and macros for manipulating the floating-point environment.[1]

This header declares two types, fenv_t (represents the whole floating-point environment) and fexcept_t (represents the floating-point status flags).[1] It also declares several feature macros, beginning with FE_ and a capital letter.

Functions

Other than fegetround and fetestexcept, these functions return zero/non-zero on success/failure.

DeclarationDescription
int feclearexcept(int excepts);clear exceptions specified by excepts
int fegetenv(fenv_t *penv);store current floating-point environment in penv
int fegetexceptflag(fexcept_t *pflag, int excepts);store current status flags in pflags
int fegetround(void);retrieve current rounding direction
int feholdexcept(fenv_t *penv);save current floating-point environment to penv and clear all exceptions
int feraiseexcept(int excepts);raise floating-point exceptions
int fesetenv(const fenv_t *penv);set current floating-point environment to penv
int fesetexceptflag(const fexcept_t *pflags, int excepts);set current status flags to those stored in pflags
int fesetround(int round);set current rounding direction to round
int fetestexcept(int excepts);test whether certain exceptions have been raised
int feupdateenv(const fenv_t *penv);restore floating-point environment penv, but keep current exceptions
int fesetprec(int prec)Sets the precision mode to the value specified by prec.

References

  1. 1 2 fenv.h: floating-point environment – Base Definitions Reference, The Single UNIX® Specification, Issue 7 from The Open Group
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