swift - 协助 Swift 中的变量

Question

我是第一个计算机科学类的学生。我想弄清楚如何设置变量，以便它接受一个数字，该数字附加到我们老师设置的命令 ./integerProperties 。请查看我编写的代码，我可以使用一些帮助来了解如何获取该输入并将其插入我名为 number 的变量中。

27 │Example output for:  ./integerProperties 1983
28 │
29 │    The number is even:
30 │    false
31 │    The number is odd:
32 │    true
33 │    The number is evenly divisible by three:
34 │    true
35 │    The number is evenly divisible by five:
36 │    false
37 │    The number is evenly divisible by seven:
38 │    false
39 │    How many groups of ten?
40 │    198
41 │    How many groups of hundred?
42 │    19
43 │    The additive inverse:
44 │    -1983
45 │
46 │
47 │
48 │    */
49 │ let firstParameter = CommandLine.arguments[1]
50 │ var number: Int
51 │
52 │ print("The number is even:")
53 │ print(number % 2 == 0)
54 │ print("The number is odd ")
55 │ print(number % 2 != 0)
56 │ print("the number is evenly divisible by 3")
57 │ print(number % 3 == 0)
58 │ print("the number is evenly divisible by 5")
59 │ print(number % 5 == 0)
60 │ print("the number of evenly divisible by 7")
61 │ print(number % 7 == 0)
62 │ print("how many groups of ten")
63 │ print(number / 10)
64 │ print("how many groups of hundreds")
65 │ print(number / 100)
66 │ print("the additive inverse")
67 │ print(number * -1)

Answer 1

使用 Int(String) 将参数解析为整数。请注意，如果字符串不是整数，它将返回 nil Int?，您应该处理这种情况。

guard let number = Int(firstParameter) else {
    fatalError("firstParameter is not an Int")
}

编辑:您还应该检查参数是否存在，否则 CommandLine.arguments[1] 将因索引超出范围而失败。