The fmod() function in C computes the floating-point remainder of the division of two numbers. It is part of the math library <math.h> in C and <cmath> in C++.

fmod() in C

The fmod() function returns the remainder of the division of two floating-point numbers. It is particularly useful when dealing with periodic functions, angles, or any scenario where the remainder after division is required.

Syntax of fmod() in C

double fmod(double x, double y);

Parameters

The method accepts the following parameters:

• x: The dividend, a floating-point number.
• y: The divisor, a floating-point number.

Return Value

The fmod() function returns the remainder of the division x / y as a double. The result has the same sign as the dividend x.

Examples of fmod() Function in C

Example 1

The below program illustrates how to calculate the remainder of the division of two given numbers using the fmod(x, y) function in C:

// C Program to calculate the remainder using fmod() function

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

int main()
{
    // Initialize variables to take the input from the user
    // and store the results
    double x, y, remainder;

    // Take the input from the user
    printf("Enter the dividend: ");
    scanf("%lf", &x);
    
    printf("Enter the divisor: ");
    scanf("%lf", &y);

    // Calculate the remainder of the division of x by y
    remainder = fmod(x, y);

    // Print the remainder
    printf("The remainder of %.2lf divided by %.2lf is: %.2lf\n", x, y, remainder);

    return 0;
}

Output

Enter the dividend: 7.5
Enter the divisor: 2.3
The remainder of 7.50 divided by 2.30 is: 0.60

Time Complexity: O(1)
Auxiliary Space: O(1)

Example 2

The below program illustrates how to find the remainder for different data types in C.

// C program to calculate the remainder of different data
// types in C using fmod() function

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

int main()
{
    // Initialize variables of different data types
    double x1 = 10.5, y1 = 5.5;
    float x2 = 10.5f, y2 = 5.5f;
    long double x3 = 10.5l, y3 = 5.5l;

    // Calculate the remainder using the appropriate fmod
    // function for each data type

    // fmod function for double
    double result1 = fmod(x1, y1);

    // fmodf function for float
    float result2 = fmodf(x2, y2);

    // fmodl function for long double
    long double result3 = fmodl(x3, y3);

    // Print the results
    printf("The remainder of %.2f divided by %.2f is %.2f\n", x1, y1, result1);
    printf("The remainder of %.2f divided by %.2f is %.2f\n", x2, y2, result2);
    printf("The remainder of %.2Lf divided by %.2Lf is %.2Lf\n", x3, y3, result3);

    return 0;
}

The remainder of 10.50 divided by 5.50 is 5.00
The remainder of 10.50 divided by 5.50 is 5.00
The remainder of 10.50 divided by 5.50 is 5.00

Time Complexity: O(1)
Auxiliary Space: O(1)

Conclusion

The fmod() function is essential when you need to obtain the remainder of a floating-point division. It ensures precision in calculations involving periodic values, such as angles in trigonometry.

Frequently Asked Questions on C floor() Function

What happens if the divisor y is zero?

If the divisor y is zero, the behavior of fmod() is undefined, and it may result in a domain error.

Can fmod() handle negative numbers?

Yes, fmod() can handle negative numbers. The sign of the result is the same as the sign of the dividend x.

Is there an alternative to fmod() in C++?

Yes, in C++, you can use the std::fmod() function from the <cmath> library, which behaves similarly to fmod() in C.