如何使用 for 循环在 Swift 3 中创建 Int 数组

Question

I know this is a very basic question,

But I try lot methods, and always show:

"fatal error: Array index out of range"

I want to create a 0~100 int array

eq var integerArray = [0,1,2,3,.....,100]

and I trying

var integerArray = [Int]()
for i in 0 ... 100{
integerArray[i] = i
}

There are also appear : fatal error: Array index out of range

Thanks for help

Complete code:

class AlertViewController: UIViewController,UIPickerViewDelegate, UIPickerViewDataSource {

@IBOutlet weak var integerPickerView: UIPickerView!
@IBOutlet weak var decimalPickerView: UIPickerView!

var integerArray = [Int]()
var decimalArray = [Int]()

override func viewDidLoad() {
    super.viewDidLoad()
    giveArrayNumber()
    integerPickerView.delegate = self
    decimalPickerView.delegate = self
    integerPickerView.dataSource = self
    decimalPickerView.dataSource = self
}

func giveArrayNumber(){
    for i in 0 ... 100{
        integerArray[i] = i
    }
}

Answer 1

Your array is empty and you are subscripting to assign value thats why you are getting "Array index out of range" crash. If you want to go with for loop then.

var integerArray = [Int]()
for i in 0...100 {
    integerArray.append(i)
}

But instead of that you can create array simply like this no need to use for loop .

var integerArray = [Int](0...100)

Answer 2

Without using loops:

var integerArray = Array(0...100)

Without using loops 2:

var integerArray = (0...100).map{ $0 }

Without using loops 3:

var integerArray = [Int](0...100)

Using loops:

var integerArray = [Int]()
for i in 0...100 { integerArray.append(i) }

Answer 3

Because your array is empty, so the " integerArray[i] (where i is 1 for example)" doesn't exist.

You have to write something like this :

 func giveArrayNumber() {
    for i in 0 ... 100{
       integerArray.append(i)
    }
 }