Assistance with variable in Swift

Question

I am a student in my first computer science class. I am trying to figure out how to set the variable so that it takes a number that is attached to a command our teacher set up called ./integerProperties . Please look at the code I have written, I could use some assistance in how to take that input, and plug it into my variable called number.

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

Use Int(String) to parse the argument to an integer. Note that if the string is not an integer, it will return a nil Int?, and you should handle this case.

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

Edit: You should also check that the parameter even exists, otherwise CommandLine.arguments[1] will fail with index out of bounds.