Contents

isLess(than:)

Returns a Boolean value indicating whether this instance is less than the given value.

Declaration

func isLess(than other: Self) -> Bool

Parameters

  • other:

    The value to compare with this value.

Return Value

true if this value is less than other; 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 less-than operator (<) for floating-point values. Some special cases apply:

  • Because NaN compares not less than nor greater than any value, this method returns false when called on NaN or when NaN is passed as other.

  • -infinity compares less than all values except for itself and NaN.

  • Every value except for NaN and +infinity compares less than +infinity.

The following example shows the behavior of the isLess(than:) method with different kinds of values:

let x = 15.0
x.isLess(than: 20.0)
// true
x.isLess(than: .nan)
// false
Double.nan.isLess(than: x)
// false

The isLess(than:) method implements the less-than predicate defined by the IEEE 754 specification.