CODEWITHSUNDEEP
swiftfieldofview
wupiupi
wupiupi

Reputation: 69

How to remove a variable from the field of view

while true {
print ( """
1. Log in
2. Create new user
3. Quit
""")
if let numberString = readLine(), let number = Int(numberString) {
    print("you entered \(number)")
    break
} else {
    print("Try again")
}
}

It is necessary to use the number variable in the future to compare it. How can it be taken out of sight?

When I try to make a global var something goes wrong:

var numberString: String?
var number: Int?

while true {
print ( """
1. Log in
2. Create new user
3. Quit
""")
if numberString = readLine(), number = Int(numberString) {
    print("you entered \(number)")
    break
} else {
    print("Try again")
}
}

enter image description here

Upvotes: -1

Views: 388

Answers (2)

Leo Dabus
Leo Dabus

Reputation: 236360

Considering that you are creating a command prompt and that choice has no meaning outside your loop there is no need to make it global. You only need to switch the user selection and decide what to do from there. Note that if you try to break from inside the switch you won't exit your loop as I showed to you in your last question. To allow the compiler to know that you want to break the while loop instead of the switch you need to label your while loop statement, this way you can specify what you want to break when you have a switch inside a loop. Try like this:

func getValue() -> Int? {
    guard let line = readLine(), let value = Int(line) else {
        return nil
    }
    return value
}

question: while true {
    print("""
          1. Log in
          2. Create new user
          3. Quit
          """)
    guard let value = getValue() else {
        continue
    }
    switch value {
    case 1:
        print("you have selected number one")
    case 2:
        print("you have selected number two")
    case 3:
        print("Good bye")
        break question
    default:
        print("Try again")
    }
}

Upvotes: 1

Euan
Euan

Reputation: 618

There is not much information to go off of here, but I think I can help. In the first script, you are creating a new variable and setting the value for that variable:

if let numberString = readLine(), let number = Int(numberString) { ... }

In your second script, you have to global variables, but at no point have you provided them a value. What you need to do is provide both global variables (numberString and number) a value before comparing them. As such, you need to use the == sign to compare different variables/ types. For instance:

var numberString: String?
var number: Int?

while true {
    print("""
    1. Log in
    2. Create new user
    3. Quit
    """)
    numberString = readLine()
    number = Int(numberString!)
}

You can now compare and or print your global variables...

Final Code

var numberString: String?
var number: Int?

while true {
    print("""
    1. Log in
    2. Create new user
    3. Quit
    """)
    numberString = readLine()
    number = Int(numberString!)
    
    if number == 1 {
        print("you have selected number one")
    } else if number == 2 {
        print("you have selected number two")
    } else if number == 3 {
        print("you have selected number three")
    } else {
        print("Try again")
    }
}

Due to the fact that both variables numberString and number are now global variables, you can access them in the future if you need to compare them again.

Upvotes: 0

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