Swift Tutorial Swift References

Swift - fmod() Function

The Swift 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.


In Foundation framework, it is defined as follows:

public func fmod<T>(_ x: T, _ y: T) -> T 
//where T : FloatingPoint


x Specify the value of numerator.
y Specify the value of denominator.

Return Value

Returns remainder of x/y. If y is zero, the function returns -nan.


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

import Foundation

print("fmod(25.0, 4.0) = \(fmod(25.0, 4.0))")
print("fmod(27.0, 4.0) = \(fmod(27.0, 4.0))")
print("fmod(-6.0, 5.0) = \(fmod(-6.0, 5.0))")
print("fmod(-9.0, 5.0) = \(fmod(-9.0, 5.0))")
print("fmod(10.0, 0.0) = \(fmod(10.0, 0.0))")

The output of the above code will be:

fmod(25.0, 4.0) = 1.0
fmod(27.0, 4.0) = 3.0
fmod(-6.0, 5.0) = -1.0
fmod(-9.0, 5.0) = -4.0
fmod(10.0, 0.0) = -nan

❮ Swift Math Functions