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Table of contents
What is round() Function in C?
Important Considerations
Frequently Asked Questions 
What happens if the number is exactly halfway between two integers?
Can the round() function handle negative numbers?
Does the round() function work with all numeric data types in C?
Last Updated: Mar 27, 2024

C round() Function

Author Sinki Kumari
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In any programming language, functions serve as the building blocks of code. They allow us to perform specific tasks with a certain set of inputs. Among the rich repertoire of functions in the C library, one of the most commonly used functions is the round() function. This function is used to round off floating-point numbers to the nearest integer. 

 C round() ffunction

In this article, we will delve into the workings of the round() function in C, demonstrating its use with a simple code snippet, and answering some of the frequently asked questions about it.

What is round() Function in C?

The round() function is a mathematical function, it's a part of the <math.h> in C library. round() Function in C round a floating-point number to its nearest integral value. If the fractional part of the number is 0.5 or above, the function rounds it up to the next integer; otherwise, it rounds it down.

To use the round() function, we first need to include the math.h library in our code:

#include <math.h>

//Here's a simple use case of the round() function:

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

int main() {
    double num = 5.7;
    double result;

    result = round(num);
    printf("Rounded value of %.1f is %.1f\n", num, result);

    return 0;



In the above program, the round() function rounds the number 5.7 up to the nearest whole number, which is 6.0.

Also read - Bit stuffing program in c

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Important Considerations

While the round() function is straightforward, there are a few important things to consider:

The argument: The round() function takes a single argument, which is the number you want to round off. This number can be a floating-point value (either float or double).

Return value: The function returns the rounded integral value in double data type.

Library inclusion: Don't forget to include the math.h library in your code, as round() is a standard mathematical function.

Also see, Floyd's Triangle in C

Frequently Asked Questions 

What happens if the number is exactly halfway between two integers?

In C, if a number is exactly halfway between two integers, the round() function rounds it to the nearest even number. This method is known as "round half to even".

Can the round() function handle negative numbers?

Yes, the round() function can handle negative numbers. It rounds them to the nearest integer, following the same rules for positive numbers.

Does the round() function work with all numeric data types in C?

No, the round() function works with floating-point numbers, i.e., float and double types. It does not accept integers, characters, or strings.


The round() function is a handy tool in the C language for manipulating numerical data. It allows us to handle floating-point numbers effectively, rounding them to the nearest integer. It's essential to remember its syntax, return type, and necessary library inclusion, as well as how it behaves with different types of numbers. Understanding the basic tools and functions available in C, such as round(), will enable you to solve a wide array of programming problems with ease and proficiency. 

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