In this C++ tutorial, you will learn how to round a given number to nearest integer value using round() function of cmath, with syntax and examples.

C++ round()

C++ round() returns integer value nearest to given value. Half-way (0.5) cases are rounded to higher nearest integer.


The syntax of C++ round() is



xA double, float, long double, or IntegralType value.


The return value depends on the type of value passed for parameter x. The return value of round(x) is

  • double if x is double or IntegralType.
  • float if x is float.
  • long double if x is long double.

The synopsis of round() function is

float roundf(float);
double round(double);
long double roundl(long double);

round() is a function of cmath library. Include cmath library at the start of program, if using round() function.



In this example, we read a double value from user into variable x, and find the nearest integer to this value in x, using round().

C++ Program

#include <iostream>
using namespace std;

int main() {
    double x;
    cout << "Enter a number : ";
    cin >> x;
    double result = round(x);
    cout << "round(" << x << ") : " << result << endl;


Enter a number : 3.14
round(3.14) : 3
Program ended with exit code: 0
Enter a number : 3.5
round(3.5) : 4
Program ended with exit code:
Enter a number : 3.62
round(3.62) : 4
Program ended with exit code: 0


In this C++ Tutorial, we learned the syntax of C++ round(), and how to use this function to round off given number to nearest integer value, with the help of examples.