6.7 Range Operators

Swift includes several useful operators that allow ranges of values to be declared. As will be seen in later chapters, these operators are invaluable when working with looping in program logic.

The syntax for the closed range operator is as follows:

x…y

This operator represents the range of numbers starting at x and ending at y where both x and y are included within the range. The range operator 5…8, for example, specifies the numbers 5, 6, 7 and 8.

The half-open range operator, on the other hand uses the following syntax:

x..<y

In this instance, the operator encompasses all the numbers from x up to, but not including, y. A half-closed range operator 5..<8, therefore, specifies the numbers 5, 6 and 7.

Finally, the one-sided range operator specifies a range that can extend as far as possible in a specified range direction until the natural beginning or end of the range is reached (or until some other condition is met). A...