feraiseexcept

Defined in header <fenv.h> 
int feraiseexcept( int excepts );
 (since C99)

Attempts to raise all floating point exceptions listed in excepts (a bitwise OR of the floating point exception macros). If one of the exceptions is FE_OVERFLOW or FE_UNDERFLOW, this function may additionally raise FE_INEXACT. The order in which the exceptions are raised is unspecified, except that FE_OVERFLOW and FE_UNDERFLOW are always raised before FE_INEXACT.

Parameters

excepts - bitmask listing the exception flags to raise

Return value

​0​ if all listed exceptions were raised, non-zero value 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");
    feclearexcept(FE_ALL_EXCEPT);
    printf("\n");
}
 
double some_computation(void)
{
    /* Computation reaches a state that causes overflow. */
    int r = feraiseexcept(FE_OVERFLOW | FE_INEXACT);
    printf("feraiseexcept() %s\n", (r?"fails":"succeeds"));
    return 0.0;
}
 
int main(void)
{
    some_computation();
    show_fe_exceptions();
 
    return 0;
}

Output:

feraiseexcept() succeeds
current exceptions raised:  FE_INEXACT FE_OVERFLOW

References

  • C11 standard (ISO/IEC 9899:2011):
    • 7.6.2.3 The feraiseexcept function (p: 210)
  • C99 standard (ISO/IEC 9899:1999):
    • 7.6.2.3 The feraiseexcept function (p: 191)

See also

(C99)
 clears the specified floating-point status flags
(function)
(C99)
 determines which of the specified floating-point status flags are set
(function)

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