round() Function in C

In C, the round() function is used to round a floating-point number to the nearest integer. If the fractional part of the number is 0.5 or greater, the number is rounded up; otherwise, it is rounded down. This function is part of the math.h library.

Syntax:

#include <math.h>
double round(double x);

Parameters:

• x: The floating-point number you want to round.

Return Value:

• The function returns the nearest integer value as a double. If the input is already an integer, it returns the same value.
• If x is exactly halfway between two integers, it rounds away from zero (i.e., it rounds up for positive numbers and rounds down for negative numbers).

Example:

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

int main() {
    double num1 = 3.6;
    double num2 = 3.2;
    double num3 = -3.5;
    
    printf("round(3.6) = %.0f\n", round(num1));
    printf("round(3.2) = %.0f\n", round(num2));
    printf("round(-3.5) = %.0f\n", round(num3));
    
    return 0;
}

Output:

round(3.6) = 4
round(3.2) = 3
round(-3.5) = -4

Notes:

• To use the round() function, you must include the math.h library.
• Make sure to link with the math library by using the -lm flag when compiling the program (e.g., gcc program.c -lm).

The round() function is useful for applications where you need precise rounding to the nearest integer.