# std::fegetround, std::fesetround

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< cpp‎ | numeric‎ | fenv

Defined in header `<cfenv>` |  |
int fesetround( int round ) | (1) | (since C++11)
int fegetround() | (2) | (since C++11)

Manages the floating-point rounding direction.

1) Attempts to establish the floating-point rounding direction equal to the argument `round`, which is expected to be one of the floating point rounding macros.
2) Returns the value of the floating point rounding macro that corresponds to the current rounding direction.

### Parameters

round | - | rounding direction, one of floating point rounding macros

### Return value

1) ​0​ on success, non-zero otherwise.

2) The floating point rounding macro describing the current rounding direction or a negative value if the direction cannot be determined.

### Notes

The current rounding mode, reflecting the effects of the most recent `fesetround`, can also be queried with FLT_ROUNDS.

See floating-point rounding macros for the effects of rounding.

### Example

Run this code

    #include <cfenv>
    #include <cmath>
    #include <iomanip>
    #include <iostream>
    #include <utility>
    // #pragma STDC FENV_ACCESS ON

    int main()
    {
        static constexpr std::pair<const char*, const double> samples[]
        {
            {" 12.0", 12.0},  {" 12.1", 12.1}, {"-12.1", -12.1}, {" 12.5", 12.5},
            {"-12.5", -12.5}, {" 12.9", 12.9}, {"-12.9", -12.9}, {" 13.0", 13.0}
        };

        std::cout <<
            "│ sample │  FE_DOWNWARD  │   FE_UPWARD   │ FE_TONEAREST  │ FE_TOWARDZERO │\n";

        for (const auto& [str, fp] : samples)
        {
            std::cout << "│ " << std::setw(6) << str << " │  ";
            for (const int dir : {FE_DOWNWARD, FE_UPWARD, FE_TONEAREST, FE_TOWARDZERO})
            {
                std::fesetround(dir);
                std::cout << std::setw(10) << std::fixed << std::nearbyint(fp) << "   │  ";
            }
            std::cout << '\n';
        }
    }

Output:

    │ sample │  FE_DOWNWARD  │   FE_UPWARD   │ FE_TONEAREST  │ FE_TOWARDZERO │
    │   12.0 │   12.000000   │   12.000000   │   12.000000   │   12.000000   │
    │   12.1 │   12.000000   │   13.000000   │   12.000000   │   12.000000   │
    │  -12.1 │  -13.000000   │  -12.000000   │  -12.000000   │  -12.000000   │
    │   12.5 │   12.000000   │   13.000000   │   12.000000   │   12.000000   │
    │  -12.5 │  -13.000000   │  -12.000000   │  -12.000000   │  -12.000000   │
    │   12.9 │   12.000000   │   13.000000   │   13.000000   │   12.000000   │
    │  -12.9 │  -13.000000   │  -12.000000   │  -13.000000   │  -12.000000   │
    │   13.0 │   13.000000   │   13.000000   │   13.000000   │   13.000000   │

### See also

nearbyint nearbyintf nearbyintl (C++11)(C++11)(C++11) | nearest integer using current rounding mode (function)
rint rintf rintl lrint lrintf lrintl llrint llrintf llrintl (C++11)(C++11)(C++11)(C++11)(C++11)(C++11)(C++11)(C++11)(C++11) | nearest integer using current rounding mode with exception if the result differs (function)

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