C round() Function

Posted in C Tutorial

Updated on Jan 13, 2024

By Mari Selvan

👁️ 646 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In C programming, the round() function is part of the <math.h> library and is used for rounding floating-point numbers to the nearest integer.

This function is particularly useful when you need to perform arithmetic operations that result in non-integer values, and you want to round the result to the nearest whole number.

In this tutorial, we'll explore the usage and functionality of the round() function in C.

💡 Syntax

The syntax for the round() function is as follows:

Syntax

Copied

double round(double x);

x: The floating-point number to be rounded.

📄 Example

Let's dive into an example to illustrate how the round() function works.

round.c

Copied

#include <stdio.h>
#include <math.h>

int main() {
  double number = 15.67;

  // Round the number
  double roundedNumber = round(number);

  // Output the result
  printf("Original number: %.2f\n", number);
  printf("Rounded number: %.0f\n", roundedNumber);

  return 0;
}

💻 Output

Output

Original number: 15.67
Rounded number: 16

🧠 How the Program Works

In this example, the round() function is used to round the floating-point number 15.67 to the nearest integer, and the result is printed.

↩️ Return Value

The round() function returns a double value representing the rounded integer. The return type is double to accommodate the possibility of rounding to a non-integer value.

📚 Common Use Cases

The round() function is commonly used in scenarios where precise arithmetic operations result in non-integer values, but the application requires an integer result. For example, when dealing with financial calculations or measurements that should be represented as whole numbers.

📝 Notes

The round() function rounds towards the nearest integer. If the fractional part is exactly 0.5, the function rounds to the nearest even integer (a method known as "round to even" or "bankers' rounding").
For rounding towards positive infinity, the ceil() function can be used, and for rounding towards negative infinity, the floor() function is suitable.

🎢 Optimization

The round() function is generally efficient, but be cautious when using it in performance-critical sections of code. If you are only interested in obtaining the integer part of a floating-point number, consider using type casting ((int)) or the floor() or ceil() functions.

🎉 Conclusion

The round() function in C is a valuable tool for rounding floating-point numbers to the nearest integer. It ensures that results are represented in a way that makes sense for the specific application, especially when dealing with calculations that involve non-integer values.

Feel free to experiment with different floating-point numbers and explore the behavior of the round() function in various scenarios. Happy coding!