为什么在遍历多维数组时 for 循环会中断？

Question

我想做的是创建一个由数组组成的可编辑日历。

首先我创建了一些变量：

import UIKit

/////////////////////////////////////////////////////////////////////

// Variables

var userName = "String"
var bedTime: Int = 0
var wakeTime: Int = 7
var sleepMonth = "String"
var quantifiedMonth: Int = 1

然后是多维数组的日历：

var day0: [Int] = [0]
var day1: [Int] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]
var day2: [Int] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]
var day3: [Int] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]
var day4: [Int] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]

var month0 = [[0]]
var january = [day0, day1, day2, day3, day4]
var february = [day0, day1, day2, day3, day4]
var march = [day0, day1, day2, day3, day4]
var april = [day0, day1, day2, day3, day4]
var may = [day0, day1, day2, day3, day4]
var june = [day0, day1, day2, day3, day4]
var july = [day0, day1, day2, day3, day4]
var august = [day0, day1, day2, day3, day4]
var september = [day0, day1, day2, day3, day4]
var october = [day0, day1, day2, day3, day4]
var november = [day0, day1, day2, day3, day4]
var december = [day0, day1, day2, day3, day4]

var calendar = [month0, january, february, march, april, may, june, july, august, september, october, december]

然后我尝试使用嵌套的 for 循环让用户说出他们通常在睡觉的时间：

   @IBAction func setVariablesButton(_ sender: UIButton)
    {
        bedTime = Int(bedTimeTextField.text!)!
        wakeTime = Int(wakeTimeTextField.text!)!
        quantifiedMonth = Int(monthToEditTextField.text!)!
        var hourX = bedTime
        var hourZ = wakeTime
        var dayX = 1
        let dayZ = 1
        let lengthMonth = calendar[quantifiedMonth].count

        for _ in 1...lengthMonth // Do the following for as many days
            // as are in the month
        {
            for _ in calendar[1][dayX][hourX]...calendar[1][dayX][24]
            {
                calendar[1][dayX][hourX] = 0 // Loops by amount
                hourX = hourX + 1            // specified 2 lines above
            }

            for _ in calendar[1][dayZ][0]...calendar[1][dayZ][hourZ]
            {
                calendar[1][dayX][hourZ] = 0
                hourZ = hourZ - 1
            }

            dayX = dayX + 1 // Loops by amount specified 8 lines above
        }


        bedTimeLabel.text = "\(calendar[1][1])"
    }

当我构建时，我总是

var quantifiedMonth

设置为 0，允许程序运行。然后我意识到，如果我将它设置为 1，它就会中断。由于程序运行时我得到的输出，我无法理解为什么。

说我有

var quantifiedMonth = 0
bedTime = 20
wakeTime = 7

那么我的输出将是

[0, 0, 0, 0, 0, 0, 0, 0, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 0, 0, 0, 0, 0]

但是当

var quantifiedMonth = 1

程序崩溃。我无法理解为什么会这样。在我看来，我不应该能够得到

时的输出

var quantifiedMonth = 0

请帮忙。我试图彻底回答我的问题，但如果我对某些事情含糊不清，请告诉我。

This is one of the error messages I get

Here's another one

Answer 1

问题是您在 for 循环之外声明了本应在其内部声明的变量。

        var hourX = bedTime
        var hourZ = wakeTime

应该这样声明：

    for _ in 1...lengthMonth 
    {
        var hourX = bedTime
        var hourZ = wakeTime

否则这些变量没有按应有的方式设置。

您还需要将 lengthMonth 更改为

let lengthMonth = calendar[quantifiedMonth].count - 1

因为你从 1 开始 for 循环，当你的数组从 0 开始时。否则你会得到一个 "Index out of range" 错误。

为什么在遍历多维数组时 for 循环会中断？

Why does the for-loop break when iterating through a multidimensional array?

arrays

multidimensional-array

xcode8

swift2.3