"One-sided form" 的 "half-open range operator"

Question

来自 基本运算符 — Swift 编程语言 (Swift 4.2);

The half-open range operator also has a one-sided form that’s written with only its final value. Just like when you include a value on both sides, the final value isn’t part of the range. For example:

let names = ["Anna", "Alex", "Brian", "Jack"]

// Prints "Anna" and "Alex".
for name in names[..<2] {
    print(name)
}

我的问题是； 第一个值 为什么我们不能也有这个？

// The next three lines are all valid.
var a = 0...
var b = ...0
var c = ..<0

// But this line is not, compilation error...
var d = 0<..

Answer 1

您的接线员不是正确的接线员：

var d = 0<.. /// Swift doesn't have this operator

如果你想要，你需要更多然后 0 然后使用下面：

var d = 1...
var d = 2...
var d = 3...

有关详细信息，您可以查看此 link：https://docs.swift.org/swift-book/LanguageGuide/BasicOperators.html

"One-sided form" 的 "half-open range operator"

"One-sided form" of the "half-open range operator"

operators

range

swift