What is the rint() function in C++?

Overview

In C++, the rint() function is used to round the argument x to an integral value. The argument is rounded to an integral value by making use of the current rounding mode.

Note: The current rounding mode is determined, using the fesetround() function.

Syntax

double rint(double x);
float rint(float x);
long double rint(long double x);
double rint(T x);

Parameter value

The rint() function takes a single parameter value x, which represents the value taht needs to be rounded to an integral value.

Return value

The rint() function returns a value of either type double, float, or long double.

By default, the rounding is done “to the nearest” integer.

Code example

#include <iostream>
#include <cmath>
#include <cfenv>
using namespace std;
int main()
{
  // creatinn our variables
    double x = 19.6;
    double result;
    
    // setting rounding direction to DOWNWARD using the fesetround function
    fesetround(FE_DOWNWARD);
    // using the rint() function
    result = rint(x);
    cout << "Rounding (" << x << ")  downward  = " << result << endl;
    return 0;
}

Code explanation

  • Lines 9–10: We create the variables x and result.
  • Line 13: We set the rounding direction to downward, using the fesetround() function.
  • Line 16: We implement the rint() function on the x variable and assign the output to the result variable.
  • Line 17: We print the result variable.

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