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# fegetexceptflag, fesetexceptflag

From cppreference.com
< c‎ | numeric‎ | fenv

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.

### [edit] 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

### [edit] Return value

​0​ on success, non-zero otherwise.

### [edit] Example

Run this code

    #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)

### [edit] See also

C++ documentation for fegetexceptflag, fesetexceptflag

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