CODEWITHSUNDEEP
iosswift3base-conversion
Diego Esc
Diego Esc

Reputation: 15

know the highest digit of a number

I'm doing an app in Xcode 8 with swift 3 that is a base converter, the input value is set with buttons:

@IBAction func inputButton(_ sender: UIButton)
{
    currentNumber = currentNumber * 10 + (the number I want to add)
    labelText.text = "\(currentNumber)"
}

It works perfectly, but when I input about 10 numbers the app crashes. After the line where I set the new value for "currentnumber" Xcode shows me this:

Thread1: EXC_BAD_INSTRUCTION (code=EXC_INPOV, subcode=0x0)

Upvotes: 1

Views: 82

Answers (1)

Nikolai Ruhe
Nikolai Ruhe

Reputation: 81868

Overflow is (thankfully) an error in Swift.

You can prevent this in your code by checking if values would exceed Int.max, before actually performing the calculation.

Here's some code to get you started:

guard let inputNumber = Int(inputString) else {
    labelText.text = "input not a number or out of range"
    return
}

guard currentNumber < (Int.max - inputNumber) / 10 else {
    labelText.text = "overflow"
    return
}

currentNumber = currentNumber * 10 + inputNumber
labelText.text = "\(currentNumber)"

Upvotes: 2

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