# fegetround, fesetround

Gets or sets the current floating-point rounding mode.

## Syntax

```
int fegetround(void);
int fesetround(
int round_mode
);
```

### Parameters

*round_mode*

The rounding mode to set, as one of the floating-point rounding macros. If the value is not equal to one of the floating-point rounding macros, the rounding mode is not changed.

## Return Value

On success, **fegetround** returns the rounding mode as one of the floating point rounding macro values. It returns a negative value if the current rounding mode can't be determined.

On success, **fesetround** returns 0. Otherwise, a non-zero value is returned.

## Remarks

Floating-point operations can use one of several rounding modes. These control which direction the results of floating-point operations are rounded toward when the results are stored. These are the names and behaviors of the floating-point rounding macros defined in <fenv.h>:

Macro | Description |
---|---|

FE_DOWNWARD | Round towards negative infinity. |

FE_TONEAREST | Round towards the nearest. |

FE_TOWARDZERO | Round towards zero. |

FE_UPWARD | Round towards positive infinity. |

The default behavior of FE_TONEAREST is to round results midway between representable values toward the nearest value with an even (0) least significant bit.

The current rounding mode affects these operations:

String conversions.

The results of floating-point arithmetic operators outside of constant expressions.

The library rounding functions, such as

**rint**and**nearbyint**.Return values from standard library mathematical functions.

The current rounding mode does not affect these operations:

The

**trunc**,**ceil**,**floor**, and**lround**library functions.Floating-point to integer implicit casts and conversions, which always round towards zero.

The results of floating-point arithmetic operators in constant expressions, which always round to the nearest value.

To use these functions, you must turn off floating-point optimizations that could prevent access by using the `#pragma fenv_access(on)`

directive prior to the call. For more information, see fenv_access.

## Requirements

Function | C header | C++ header |
---|---|---|

fegetround, fesetround |
<fenv.h> | <cfenv> |

For additional compatibility information, see Compatibility.

## See also

Alphabetical Function Reference

nearbyint, nearbyintf, nearbyintl

rint, rintf, rintl

lrint, lrintf, lrintl, llrint, llrintf, llrintl

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