小计算器

Question

我有代码：

@IBOutlet weak var summaryLbl: UILabel!
var actualNumber: Double = 0
var previousNumber: Double = 0
var operationMath: Bool = false
var operation = 0


@IBAction func numberPressed(_ sender: UIButton) {
    if operationMath == true
    {
        summaryLbl.text = String(sender.tag)
        actualNumber = Double(summaryLbl.text!)!
        operationMath = false
    }
    else
    {
        if summaryLbl.text == "0" {
            summaryLbl.text = ""
        }
        summaryLbl.text = summaryLbl.text! + String(sender.tag)
        actualNumber = Double(summaryLbl.text!)!
    }
}

@IBAction func buttons(_ sender: UIButton) {
    if summaryLbl.text != "" && sender.tag != 10 && sender.tag != 17
    {
        previousNumber = Double(summaryLbl.text!)!

        if sender.tag == 13
        {
            summaryLbl.text = "/";
        }
        else if sender.tag == 14
        {
            summaryLbl.text = "x";
        }
        else if sender.tag == 15
        {
            summaryLbl.text = "-";
        }
        else if sender.tag == 16
        {
            summaryLbl.text = "+";
        }

        operation = sender.tag
        operationMath = true;
    }
    else if sender.tag == 17
    {
        if operation == 13
        {
            let summary = rounding(number: previousNumber / actualNumber)
            summaryLbl.text = summary
        }
        else if operation == 14
        {
            let summary = rounding(number: previousNumber * actualNumber)
            summaryLbl.text = summary
        }
        else if operation == 15
        {
            let summary = rounding(number: previousNumber - actualNumber)
            summaryLbl.text = summary
        }
        else if operation == 16
        {
            let summary = rounding(number: previousNumber + actualNumber)
            summaryLbl.text = summary
        }
        else if operation == 11 //TODO: negative numbers
        {
            let summary = rounding(number: previousNumber + actualNumber)
            summaryLbl.text = summary
        }
        else if operation == 12 //TODO: percentages
        {
            let summary = rounding(number: (previousNumber * actualNumber) / 100)
            summaryLbl.text = summary
        }
    }
    else if sender.tag == 10
    {
        summaryLbl.text = "0"
        previousNumber = 0;
        actualNumber = 0;
        operation = 0;
    }

}
override func viewDidLoad() {
    super.viewDidLoad()
    summaryLbl.text = "0"
    previousNumber = 0;
    actualNumber = 0;
    operation = 0;
}

func rounding (number: Double) -> String {
    let numberAfterRounding = String(number)
    return numberAfterRounding
}

我正在做一个小型计算器。

我有一个问题：

1. 我总是得到一个结果，例如5.0,25.0,18.0（提示：.0） - 如何摆脱它？
2. 如何制作加/负数？按下按钮操作后== 11我希望数字变为负数，或者如果它为负数则为正数（就像在iPhone中使用Apple计算器一样）
3. 百分比对我来说真的不起作用:(

Answer 1

问题1的答案： 假设您有3.0的结果并且您想要显示"3"而不是"3.0"，而对于1.23，您想要显示"1.23"。首先对数字进行检查，检查舍入数字和结果是否相同。如果它们相同，则将其转换为Int并对其进行插值。这是代码。

let result: Double = 3.0
let rounded = result.rounded()
if (result == rounded) { yourLabel.text = "\(Int(result))" }
else { yourLabel.text = "\(result)" }

问题2的答案： Swift具有negate()功能，可以完全满足您的需求。

var result: Double = 30
result.negate() // it's now -30
result.negate() // it's now 30 again

问题3的答案： 我假设当你说百分比（％）时，你的意思是模数。在swift中，你不能在像3.0 % 1.0这样的浮点上使用％（模数运算符）。相反，你必须使用truncatingRemainder(dividiedBy:)函数。

result.truncatingRemainder(dividedBy: 10) // can be any number you like