feupdateenv
From cppreference.com
Defined in header <fenv.h>
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int feupdateenv( const fenv_t* envp ); |
(since C99) | |
First, remembers the currently raised floating-point exceptions, then restores the floating-point environment from the object pointed to by envp
(similar to fesetenv), then raises the floating-point exceptions that were saved.
This function may be used to end the non-stop mode established by an earlier call to feholdexcept.
Parameters
envp | - | pointer to the object of type fenv_t set by an earlier call to feholdexcept or fegetenv or equal to FE_DFL_ENV
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Return value
0 on success, non-zero otherwise.
Example
Run this code
#include <stdio.h> #include <fenv.h> #include <float.h> #pragma STDC FENV_ACCESS ON void show_fe_exceptions(void) { printf("current exceptions raised: "); if(fetestexcept(FE_DIVBYZERO)) printf(" FE_DIVBYZERO"); if(fetestexcept(FE_INEXACT)) printf(" FE_INEXACT"); if(fetestexcept(FE_INVALID)) printf(" FE_INVALID"); if(fetestexcept(FE_OVERFLOW)) printf(" FE_OVERFLOW"); if(fetestexcept(FE_UNDERFLOW)) printf(" FE_UNDERFLOW"); if(fetestexcept(FE_ALL_EXCEPT)==0) printf(" none"); printf("\n"); } double x2 (double x) /* times two */ { fenv_t curr_excepts; /* Save and clear current f-p environment. */ feholdexcept(&curr_excepts); /* Raise inexact and overflow exceptions. */ printf("In x2(): x = %f\n", x=x*2.0); show_fe_exceptions(); feclearexcept(FE_INEXACT); /* hide inexact exception from caller */ /* Merge caller's exceptions (FE_INVALID) */ /* with remaining x2's exceptions (FE_OVERFLOW). */ feupdateenv(&curr_excepts); return x; } int main(void) { feclearexcept(FE_ALL_EXCEPT); feraiseexcept(FE_INVALID); /* some computation with invalid argument */ show_fe_exceptions(); printf("x2(DBL_MAX) = %f\n", x2(DBL_MAX)); show_fe_exceptions(); return 0; }
Output:
current exceptions raised: FE_INVALID In x2(): x = inf current exceptions raised: FE_INEXACT FE_OVERFLOW x2(DBL_MAX) = inf current exceptions raised: FE_INVALID FE_OVERFLOW
References
- C11 standard (ISO/IEC 9899:2011):
- 7.6.4.4 The feupdateenv function (p: 214-215)
- C99 standard (ISO/IEC 9899:1999):
- 7.6.4.4 The feupdateenv function (p: 195-196)
See also
(C99) |
saves the environment, clears all status flags and ignores all future errors (function) |
(C99) |
saves or restores the current floating point environment (function) |
(C99) |
default floating-point environment (macro constant) |