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[Rework]: Array #704

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var oddInts = [1, 3, 5, 7, 9, 11, 13]
oddInts.append(15)
// oddInts is now [1, 3, 5, 7, 9, 11, 13, 15]
```
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What about the following way to append an item.

var x = [1]
let y = [2]
x += y
print(x)

I believe it's much easier to reason about.

An explanation why += works as expected.

struct Vector
{
    var x: Double = 0
    var y: Double = 0

    init(x: Double, y: Double)
    {
        self.x = x
        self.y = y
    }
}
func += (left: inout Vector, right: Vector)
{
  left.x += right.x
  left.y += right.y
}

// 11
## Converting an Array to a String and Back

An array ofn strings can be converted to a single string using the [`joined(separator:)`][joined] method.
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Suggested change
An array ofn strings can be converted to a single string using the [`joined(separator:)`][joined] method.
An array of n strings can be converted to a single string using the [`joined(separator:)`][joined] method.

## Converting an Array to a String and Back

An array ofn strings can be converted to a single string using the [`joined(separator:)`][joined] method.
The `joined(separator:)` property takes a single argument, the separator to be used between elements of the array.
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Suggested change
The `joined(separator:)` property takes a single argument, the separator to be used between elements of the array.
The `joined(separator:)` method takes a single argument, the separator to be used between elements of the array.

## Converting an Array to a String and Back

An array ofn strings can be converted to a single string using the [`joined(separator:)`][joined] method.
The `joined(separator:)` property takes a single argument, the separator to be used between elements of the array.
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Suggested change
The `joined(separator:)` property takes a single argument, the separator to be used between elements of the array.
The `joined(separator:)` property takes a single argument, the separator to be used between elements of the array.
> Don't forget to convert you Array to `Array<String>`, otherwise `joined(separator:)` won't work.

Here is a snippet, that shows the conversion. This might be too complicated at this early stage.

let evenInts = [2, 4, 6, 8, 10, 12]
let evenIntsString = evenInts.map({"\($0)"}).joined(separator: ", ")


Arrays are one of Swift's three primary collection types. Arrays are ordered lists of elements where the elements can be of any type, however, all elements of any given list must have the same type.
[Arrays][array] are one of Swift's three primary collection types.
Arrays are ordered lists of elements where the elements can be of any type, however, all elements of any given list must have the same type.
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We can add a note how this is achieved and that Generics will be introduced later. For example:

Suggested change
Arrays are ordered lists of elements where the elements can be of any type, however, all elements of any given list must have the same type.
Arrays are ordered lists of elements where the elements can be of any type, however, all elements of any given list must have the same type.
> All primary collection types are implemented using generics. This is the reason why they can work with elements from already defined types or new data types that you will define.

Comment on lines -5 to +6
To make things a bit easier she only uses the cards 1 to 10.
To make things a bit easier she only uses the cards 1 to 10 so her stack of cards can be represented by an array of numbers.
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Why not using Strings. Each card can be represented by a String? What's the difference?

@@ -1,93 +1,94 @@
# Instructions

As a magician-to-be, Elyse needs to practice some basics. She has a stack of cards that she wants to manipulate.
As a magician-to-be, Elyse needs to practice some basics.
She has a stack of cards that she wants to manipulate.
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She has a stack of cards that she wants to manipulate.
She has a stack of cards that she wants to manipulate. The stack of cards can be represented by an array of strings, because regular cards contains numbers ( 1 to 10) and Jack, Queen and King, which we can denote with "J", "Q" and "K". To make it more fun you can use emojis. For example: "♦️J"

```

[array]: https://developer.apple.com/documentation/swift/array
[count]: https://developer.apple.com/documentation/swift/array/count
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[count]: https://developer.apple.com/documentation/swift/array/count
[count]: https://developer.apple.com/documentation/swift/array/count
[isEmpty]: https://developer.apple.com/documentation/swift/array/isEmpty

let emptyArray2 = Array<Int>()
let emptyArray3: [Int] = []
```

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Suggested change
An array can be checked if it's empty with [`isEmpty`][isEmpty] property.

Comment on lines +7 to +23
class TaskGetCardTests: XCTestCase {
func testGetFirstCard() {
let stack = [1, 2, 3, 4, 5]
XCTAssertEqual(getCard(at: 0, from: stack), 1)
}

func testSetCard() throws {
func testGetMiddleCard() {
let stack = [1, 2, 3, 4, 5]
XCTAssertEqual(getCard(at: 2, from: stack), 3)
}

func testGetLastCard() {
let stack = [1, 2, 3, 4, 5]
XCTAssertEqual(getCard(at: 4, from: stack), 5)
}
}

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All the tests should be revisited if the cards are represented as strings.

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2 participants