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# std::nearbyint

From cppreference.com
< cpp‎ | numeric‎ | math

Defined in header `<cmath>` |  |
float nearbyint( float arg ); |  | (since C++11)
double nearbyint( double arg ); |  | (since C++11)
long double nearbyint( long double arg ); |  | (since C++11)
double nearbyint( Integral arg ); |  | (since C++11)

Rounds the floating-point argument `arg` to an integer value in floating-point format, using the current rounding mode.

### [edit] Parameters

arg | - | floating point value

### [edit] Return value

The integer result of rounding `arg`

### [edit] Notes

The only difference between std::nearbyint and std::rint is that std::rint may raise the FE_INEXACT floating-point exception, while std::nearbyint never raises it.

### [edit] Example

[edit]
Run this code

    #include <cmath>
    #include <cfenv>
    #include <iostream>

    int main()
    {
        #pragma STDC FENV_ACCESS ON
        std::fesetround(FE_DOWNWARD);
        std::cout << "rounding using FE_DOWNWARD: \n" << std::fixed
                  << " 12.0 ->  " << std::nearbyint(12.0) << '\n'
                  << " 12.1 ->  " << std::nearbyint(12.1) << '\n'
                  << "-12.1 -> " << std::nearbyint(-12.1) << '\n'
                  << " 12.5 ->  " << std::nearbyint(12.5) << '\n'
                  << " 12.9 ->  " << std::nearbyint(12.9) << '\n'
                  << "-12.9 -> " << std::nearbyint(-12.9) << '\n'
                  << " 13.0 ->  " << std::nearbyint(13.0) << '\n';
        std::fesetround(FE_TONEAREST);
        std::cout << "rounding using FE_TONEAREST: \n"
                  << " 12.0 ->  " << std::nearbyint(12.0) << '\n'
                  << " 12.1 ->  " << std::nearbyint(12.1) << '\n'
                  << "-12.1 -> " << std::nearbyint(-12.1) << '\n'
                  << " 12.5 ->  " << std::nearbyint(12.5) << '\n'
                  << " 12.9 ->  " << std::nearbyint(12.9) << '\n'
                  << "-12.9 -> " << std::nearbyint(-12.9) << '\n'
                  << " 13.0 ->  " << std::nearbyint(13.0) << '\n';
    }

Output:

    rounding using FE_DOWNWARD:
     12.0 ->  12.000000
     12.1 ->  12.000000
    -12.1 -> -13.000000
     12.5 ->  12.000000
     12.9 ->  12.000000
    -12.9 -> -13.000000
     13.0 ->  13.000000
    rounding using FE_TONEAREST:
     12.0 ->  12.000000
     12.1 ->  12.000000
    -12.1 -> -12.000000
     12.5 ->  12.000000
     12.9 ->  13.000000
    -12.9 -> -13.000000
     13.0 ->  13.000000

### [edit] See also

rint lrint llrint (C++11)(C++11)(C++11) | nearest integer using current rounding mode with exception if the result differs (function) [edit]
round lround llround (C++11)(C++11)(C++11) | nearest integer, rounding away from zero in halfway cases (function) [edit]
fegetround fesetround (C++11)(C++11) | gets or sets rounding direction (function) [edit]

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