FunctionSwift

# stride(from:through:by:)

Returns a sequence from a starting value toward, and possibly including, an end value, stepping by the specified amount.

``func stride<T>(from start: T, through end: T, by stride: T.Stride) -> StrideThrough<T> where T : Strideable``

## Parameters

start

The starting value to use for the sequence. If the sequence contains any values, the first one is `start`.

end

An end value to limit the sequence. `end` is an element of the resulting sequence if and only if it can be produced from `start` using steps of `stride`.

stride

The amount to step by with each iteration. A positive `stride` iterates upward; a negative `stride` iterates downward.

## Returns

A sequence from `start` toward, and possibly including, `end`. Each value in the sequence is separated by `stride`.

## Overview

You can use this function to stride over values of any type that conforms to the `Strideable` protocol, such as integers or floating-point types. Starting with `start`, each successive value of the sequence adds `stride` until the next value would be beyond `end`.

``````for radians in stride(from: 0.0, through: .pi * 2, by: .pi / 2) {
let degrees = Int(radians * 180 / .pi)
}

You can use `stride(from:through:by:)` to create a sequence that strides upward or downward. Pass a negative value as `stride` to create a sequence from a higher start to a lower end:

``````for countdown in stride(from: 3, through: 1, by: -1) {
print("\(countdown)...")
}
// 3...
// 2...
// 1...``````

The value you pass as `end` is not guaranteed to be included in the sequence. If stepping from `start` by `stride` does not produce `end`, the last value in the sequence will be one step before going beyond `end`.

``````for multipleOfThree in stride(from: 3, through: 10, by: 3) {
print(multipleOfThree)
}
// 3
// 6
// 9``````

If you pass a value as `stride` that moves away from `end`, the sequence contains no values.

``````for x in stride(from: 0, through: 10, by: -1) {
print(x)
}
// Nothing is printed.``````