What is the fmod() function in C++?

Overview

The fmod() function is used to return the modulus value of a fraction of two floating-point numbers (x/y) passed to the function as an argument.

In simple terms, the fmod() function returns the floating-point remainder of xy\frac{x}{y}.

Syntax

double fmod(double x, double y);
float fmod(float x, float y):
long double fmod(long double x, long double y);

Parameter value

The fmod() function takes two arguments (x and y) as its parameter values, where x and y represent the numerator and denominator, respectively.

Return value

The fmod() function returns the floating-point remainder or modulus of x and y. It returns a NaN value i.e (Not a Number) when the denominator y is given as zero.

Example

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
    long double x = 10.55, y = 2.65;
    // using the fmod() function
    long double result = fmod(x, y);
    cout << "fmod(10.55, 2.65) = " << result << endl;
    
    x = -14.88, y = 2.06;
    // using the fmod() function
    result = fmod(x, y);
    cout << "fmod(-14.88, 2.06) =" << result << endl;
    
    return 0;
}

Code explanation

  • Line 8: We declare two doubles, x and y.

  • Line 10: We use the fmod() function to determine the remainder of x divided by y.

  • Line 11: We print the output of the fmod() function applied on x and y.

  • Line 13: We assign new values to x and y.

  • Line 15: We use the fmod() function to determine the remainder of x divided by y.

  • Line 16: We print the output of the fmod() function applied on x and y.

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