struct Stack<Element> { var items = [Element]() mutating func push(_ item: Element) { items.append(item) } mutating func pop() -> Element { return items.removeLast() } } var stackOfStrings = Stack<String>() print("字符串元素入栈: ") stackOfStrings.push("google") stackOfStrings.push("W3xue") print(stackOfStrings.items); let deletetos = stackOfStrings.pop() print("出栈元素: " + deletetos) var stackOfInts = Stack<Int>() print("整数元素入栈: ") stackOfInts.push(1) stackOfInts.push(2) print(stackOfInts.items);