fegetexceptflag, fesetexceptflag
<fenv.h>
1) Attempts to obtain the full contents of the floating-point exception flags that are listed in the bitmask argument excepts, which is a bitwise OR of the floating-point exception macros.
2) Attempts to copy the full contents of the floating-point exception flags that are listed in excepts from flagp into the floating-point environment. Does not raise any exceptions, only modifies the flags.
The full contents of a floating-point exception flag is not necessarily a boolean value indicating whether the exception is raised or cleared. For example, it may be a struct which includes the boolean status and the address of the code that triggered the exception. These functions obtain all such content and obtain/store it in flagp in implementation-defined format.
[edit] Parameters
[edit] Return value
0 on success, non-zero otherwise.
[edit] Example
#include <stdio.h> #include <fenv.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"); } int main(void) { fexcept_t excepts; /* Setup a "current" set of exception flags. */ feraiseexcept (FE_INVALID ); show_fe_exceptions(); /* Save current exception flags. */ fegetexceptflag(&excepts,FE_ALL_EXCEPT ); /* Temporarily raise two other exceptions. */ feclearexcept (FE_ALL_EXCEPT ); feraiseexcept (FE_OVERFLOW | FE_INEXACT ); show_fe_exceptions(); /* Restore previous exception flags. */ fesetexceptflag(&excepts,FE_ALL_EXCEPT ); show_fe_exceptions(); return 0; }
Output:
current exceptions raised: FE_INVALID current exceptions raised: FE_INEXACT FE_OVERFLOW current exceptions raised: FE_INVALID
[edit] References
- C11 standard (ISO/IEC 9899:2011):
- 7.6.2.2 The fegetexceptflag function (p: 210)
- 7.6.2.4 The fesetexceptflag function (p: 211)
- C99 standard (ISO/IEC 9899:1999):
- 7.6.2.2 The fegetexceptflag function (p: 191)
- 7.6.2.4 The fesetexceptflag function (p: 192)