C++ round() – Round to Nearest Integer

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.

Syntax

The syntax of C++ round() is

round(x)

where

Parameter	Description
x	A double, float, long double, or IntegralType value.

Returns

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.

Example

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>
#include<cmath>
using namespace std;

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

Output

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

Conclusion

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.