Defined in header <<fenv.h>> | ||
---|---|---|
int fegetexceptflag( fexcept_t* flagp, int excepts ); | (1) | (since C99) |
int fesetexceptflag( const fexcept_t* flagp, int excepts ); | (2) | (since C99) |
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.
Parameters
flagp | - | pointer to an fexcept_t object where the flags will be stored or read from |
excepts | - | bitmask listing the exception flags to get/set |
Return value
0
on success, non-zero otherwise.
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
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)
See also
C++ documentation for fegetexceptflag, fesetexceptflag |
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