如何在Swift 3中为for循环中修改的数组编写for循环？ [英] How do I write a for-loop in Swift 3 for an array that I modify during the for loop?

问题描述

所以，我有一个类似于这个的for循环：

So, I have a for-loop that looks similar to this:

for var i = 0; i < results.count ; i += 1 {
   if (results[i] < 5) {
      results.removeAtIndex(i)
      i -= 1
   }
}

这曾经有效。但当我将其更改为首选的Swift 3.0语法时：

This used to work. But when I changed it to the preferred Swift 3.0 syntax:

for var i in 0..<results.count {
   if (results[i] < 5) {
      results.removeAtIndex(i)
      i -= 1
   }
}

我得到一个数组IOOBE异常，因为它不会重新检查计数并继续，直到原来的结果。 count 。

I get an array IOOBE exception because it doesn't re-check the count and continues on until the original results.count.

我该如何解决这个问题？它现在有效，但我不想在将来遇到麻烦。

How do I fix this? It works now, but I don't want to get into trouble in the future.

推荐答案

虽然解决方案正在使用过滤器是一个很好的解决方案而且它更多是 Swift-ly ，还有另一种方法，如果使用 for-in 仍然需要：

While the solution making use of filter is a fine solution and it's more Swift-ly, there is another way, if making use of for-in is, nonetheless, still desired:

var results = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

for var i in (0..<results.count).reverse()
{
    if (results[i] < 5)
    {
        results.removeAtIndex(i)
        //i -= 1
    }
}

print(results)

结果：

[5, 6, 7, 8, 9, 10]

我们可以另外省略这行 i - = 1 。

We could omit this line i -= 1 altogether, in addition.

removeAtIndex 是它不会导致数组自行重新索引就地，从而导致数组超出范围，因为t o count 未更新。

The problem with removeAtIndex within the loop is that it will not cause the array to re-index itself in-place and thus causing an array out of bounds exception due to count not being updated.

通过向后遍历，可以避免出界异常。

By traversing backwards, the out of bounds exception can thus be avoided.

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