The round() function in C++ returns the integral value that is nearest to the argument, with halfway cases rounded away from zero.
round() prototype [As of C++ 11 standard]
double round(double x); float round(float x); long double round(long double x); double round(T x); // For integral type
The round() function takes a single argument and returns a value of type double, float or long double type. This function is defined in <cmath> header file.
round() Parameters
The round() function takes a single argument value to round.
round() Return value
The round() function returns the integral value that is nearest to x, with halfway cases rounded away from zero.
Example 1: How round() works in C++?
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
double x = 11.16, result;
result = round(x);
cout << "round(" << x << ") = " << result << endl;
x = 13.87;
result = round(x);
cout << "round(" << x << ") = " << result << endl;
x = 50.5;
result = round(x);
cout << "round(" << x << ") = " << result << endl;
x = -11.16;
result = round(x);
cout << "round(" << x << ") = " << result << endl;
x = -13.87;
result = round(x);
cout << "round(" << x << ") = " << result << endl;
x = -50.5;
result = round(x);
cout << "round(" << x << ") = " << result << endl;
return 0;
}
When you run the program, the output will be:
round(11.16) = 11 round(13.87) = 14 round(50.5) = 51 round(-11.16) = -11 round(-13.87) = -14 round(-50.5) = -51
Example 2: round() function for integral types
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
int x = 15;
double result;
result = round(x);
cout << "round(" << x << ") = " << result << endl;
return 0;
}
When you run the program, the output will be:
round(15) = 15
For integral values, applying the round function returns the same value as the input. So it is not commonly used for integral values in practice.