C++ <cmath> - fmod() Function

The C++ <cmath> fmod() function returns the floating-point remainder of x/y (rounded towards zero). This can be mathematically expressed as below:

fmod = x - tquot * y

Where tquot is the result of x/y rounded toward zero.

Note: The remainder function is similar to the fmod function except the quotient is rounded to the nearest integer instead of towards zero.

Syntax

• C++98
• C++11

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

double fmod (double x, double y);
float fmod (float x, float y);
long double fmod (long double x, long double y);
//additional overloads 
double fmod (Type1 x, Type2 y);                         

Parameters

Return Value

Returns remainder of x/y. If y is zero, the function may either return zero or cause a domain error (depending on the library implementation).

Example:

In the example below, fmod() function is used to find out the remainder of a given division.

#include <iostream>
#include <cmath>
using namespace std;
 
int main (){
  cout<<fmod(25, 4)<<"\n";
  cout<<fmod(20, 4.9)<<"\n";
  cout<<fmod(20.5, 2.1)<<"\n"; 
  return 0;
}

The output of the above code will be:

1
0.4
1.6