Question

我正在尝试让标签显示数字和运算符（加号或减号或其他）和下一个数字，然后用户点击结果的等号。我得到的是第一个数字，然后当操作员被点击时（仅用加号测试），第一个数字从屏幕上删除，并在被点击时被操作符号和第二个数字替换。

有人可以帮我看看我做错了什么吗？这是我有史以来的第一个Swift项目。

class ViewController: UIViewController {
    @IBOutlet weak var outputLbl: UILabel!

    var runningNumber = ""
    var leftValue = ""
    var rightValue = ""
    var result = ""
    var currentOperation:Operation = .NULL

    override func viewDidLoad() {
        super.viewDidLoad()
        outputLbl.text = "0"
    }

    @IBAction func numberPressed(_ sender: RoundButton) {
        if runningNumber.count <= 8 {
            runningNumber += "\(sender.tag)"
            outputLbl.text = runningNumber
        }
    }

    @IBAction func allClearPressed(_ sender: RoundButton) {
        runningNumber = ""
        leftValue = ""
        rightValue = ""
        result = ""
        currentOperation = .NULL
        outputLbl.text = "0"
    }

    @IBAction func dotPressed(_ sender: RoundButton) {
        if runningNumber.contains(".") {
        } else {
            runningNumber += "."
            outputLbl.text = runningNumber
        }
    }

    @IBAction func equalPressed(_ sender: RoundButton) {
        operation(operation: currentOperation)
    }

    @IBAction func addPressed(_ sender: RoundButton) {
        operation(operation: .Add)
        runningNumber += "\("+")"
        outputLbl.text = runningNumber
    }

    @IBAction func subtractPressed(_ sender: RoundButton) {
        operation(operation: .Subtract)
    }

    @IBAction func multiplyPressed(_ sender: RoundButton) {
        operation(operation: .Multiply)
    }

    @IBAction func dividePressed(_ sender: RoundButton) {
        operation(operation: .Divide)
    }

    func operation (operation:Operation){
        if currentOperation != .NULL{
            if runningNumber != ""{
                rightValue = runningNumber
                runningNumber = ""

                if currentOperation == .Add{
                    result = "\(Double(leftValue)! + Double(rightValue)!)"
                } else if currentOperation == .Subtract{
                    result = "\(Double(leftValue)! - Double(rightValue)!)"
                } else if currentOperation == .Multiply{
                    result = "\(Double(leftValue)! * Double(rightValue)!)"
                } else if currentOperation == .Divide{
                    result = "\(Double(leftValue)! / Double(rightValue)!)"
                }
                leftValue = result
                if (Double(result)!.truncatingRemainder(dividingBy: 1) == 0){
                    result = "\(Int(Double(result)!))"
                }
                outputLbl.text = result
            }
            currentOperation = operation

        } else {
            leftValue = runningNumber
            runningNumber = ""
            currentOperation = operation
        }
    }
}

Answer 1

当您致电func addPressed时，第一个功能operation(operation: .Add)正在将您的runningNumber设置为空字符串值""。之后，runningNumber += "\("+")"被称为为您提供"" + "\("+")"的内容，这就是您的标签向您展示运营商的原因。这意味着逻辑有点破碎。您不应重置runningNumber值，或者可能添加某种保存输出字符串值的变量。

另外，我建议您优化代码，而不是使用func operation(operation: Operation)中的switch-case而不是多个if-else语句。可以帮助您提高代码的可读性。

计算器应用中显示的文本不正确

1 个答案: