如何检查数组索引是否超出范围SWIFT [重复]

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这个问题在这里已有答案:

• Swift Array - Check if an index exists 7 answers

Swift数组 - 检查索引是否存在7个答案

I want to be able to check when my array index goes out of range. The array elements are all strings, so I tried to do something like this but it doesn't work:

我希望能够检查我的数组索引何时超出范围。数组元素都是字符串,所以我尝试做这样的事情,但它不起作用:

if questions[3] != nil {
}

Can someone just show me how to check?

有人可以告诉我如何检查?

1 个解决方案

#1

Before indexing into the array, you need to check:

在索引到数组之前,您需要检查:

1. The intended index is not below 0

预期指数不低于0

2. array's count is above the intended index

数组的计数高于预期的索引

---

let intendedIndex: Int = 3

if (intendedIndex >= 0 && questions.count > intendedIndex) {
    // This line will not throw index out of range:
    let question3 = questions[intendedIndex]
}