Instance Method

isEqual(to:)

Returns a Boolean value indicating whether this instance is equal to the given value.

Required.

Declaration

func isEqual(to other: Self) -> Bool

Parameters

other

The value to compare with this value.

Return Value

true if other has the same value as this instance; otherwise, false. If either this value or other is NaN, the result of this method is false.

Discussion

This method serves as the basis for the equal-to operator (==) for floating-point values. When comparing two values with this method, -0 is equal to +0. NaN is not equal to any value, including itself. For example:

let x = 15.0
x.isEqual(to: 15.0)
// true
x.isEqual(to: .nan)
// false
Double.nan.isEqual(to: .nan)
// false

The isEqual(to:) method implements the equality predicate defined by the IEEE 754 specification.