快速致命错误:超出范围的索引(超出界限的索引)
快速致命错误:超出范围的索引(超出界限的索引)
提问于 2020-05-28 03:50:42
你好，我正在努力学习敏捷。我对javascript有一点经验，所以我尝试用我通常所做的方式来建模这个循环。这个函数实际上输出了它应该输出的内容，但是我一直收到错误消息，我不知道我做错了什么。这是我的代码：
import UIKit
let dir: [String] = ["north", "east", "south", "west"]
var num = dir.count
func move(){
for i in 0 ... num{
var holder = dir[i]
switch holder{
case "north":
print("you've moved north")
case "east":
print("you've moved east")
case "south":
print("you've moved south")
case "west":
print("you've moved west")
default:
print("where you going?")
}
if i == 3{
print("round the world")
}
}
}
move()我在最后一行"move()“上得到了这个错误
错误:执行被中断，原因: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP，subcode=0x0)。
这就是控制台的输出：
你已经向北移动了
你搬到东边去了
你搬到南方去了
你搬到西边去了
环游世界
致命错误:超出范围的索引:文件/Library/Caches/com.apple.xbs/Sources/swiftlang/swiftlang-1103.2.25.8/swift/stdlib/public/core/ContiguousArrayBuffer.swift，行444
回答 4
Stack Overflow用户
回答已采纳
发布于 2020-05-28 04:04:16
在试图访问第四个索引的代码中，由于您使用了.循环控制语法。第四个索引没有排列。
以下是有关快速循环的一些详细信息。
for index in 0...4 {
...
}上面的片段说，从0开始迭代范围，包括从0到4的4。
如果不希望包含4，则使用这个称为半开范围运算符(..<)。
for index in 0..<4 {
...
}这将从0循环到3，并停止执行。
Stack Overflow用户
发布于 2020-05-28 03:57:46
在loop...but中，有更有效的方法来更好地理解您实现了什么.
我已经更新了您的code...it将正常运行。
let dir: [String] = ["north", "east", "south", "west"]
var num = dir.count
func move(){
for i in 0..<num{
var holder = dir[i]
switch holder{
case "north":
print("you've moved north")
case "east":
print("you've moved east")
case "south":
print("you've moved south")
case "west":
print("you've moved west")
default:
print("where you going?")
}
if i == 3{
print("round the world")
}
}
}
move()产出:-
you've moved north
you've moved east
you've moved south
you've moved west
round the worldSwift中的愉快编码:-)
Stack Overflow用户
发布于 2020-05-28 04:00:40
import UIKit
class ViewController: UIViewController {
let dir: [String] = ["north", "east", "south", "west"]
override func viewDidLoad() {
super.viewDidLoad()
move()
// Do any additional setup after loading the view.
}
func move(){
for (index, element) in dir.enumerated() {
// print("Item \(index): \(element)")
switch element{
case "north":
print("you've moved north")
case "east":
print("you've moved east")
case "south":
print("you've moved south")
case "west":
print("you've moved west")
default:
print("where you going?")
}
if index == 3{
print("round the world")
}
}
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/62056744
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