override func viewDidLoad() {
        super.viewDidLoad()
  //答えラベルの初期状態は0
        myEqu.text = "0"
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
//-----------------------------------------------------------
    @IBOutlet weak var myEqu: UILabel!
    //値を補完するための変数を用意
    var x = 0
    var y = 0
    //calculationは初期状態は"none"
    var calculation = "none"
//------------------------------------------------------------
    @IBAction func Btn1(_ sender: UIButton) {
      //元の数字に10かけて1を足して、答えに反映
        x = x * 10 + 1
        myEqu.text = String(x)
    }
    @IBAction func Btn2(_ sender: UIButton) {
      //元の数字に10かけて2を足して、答えに反映
        x = x * 10 + 2
        myEqu.text = String(x)
    }
    @IBAction func Btn3(_ sender: UIButton) {
      //元の数字に10かけて3を足して、答えに反映
        x = x * 10 + 3
        myEqu.text = String(x)
    }
    @IBAction func Btn4(_ sender: UIButton) {
      //元の数字に10かけて4を足して、答えに反映
        x = x * 10 + 4
        myEqu.text = String(x)
    }
    @IBAction func Btn5(_ sender: UIButton) {
      //元の数字に10かけて5を足して、答えに反映
        x = x * 10 + 5
        myEqu.text = String(x)
    }
    @IBAction func Btn6(_ sender: UIButton) {
      //元の数字に10かけて6を足して、答えに反映
        x = x * 10 + 6
        myEqu.text = String(x)
    }
    @IBAction func Btn7(_ sender: UIButton) {
      //元の数字に10かけて7を足して、答えに反映
        x = x * 10 + 7
        myEqu.text = String(x)
    }
    @IBAction func Btn8(_ sender: UIButton) {
      //元の数字に10かけて8を足して、答えに反映
        x = x * 10 + 8
        myEqu.text = String(x)
    }
    @IBAction func Btn9(_ sender: UIButton) {
      //元の数字に10かけて9を足して、答えに反映
        x = x * 10 + 9
        myEqu.text = String(x)
    }
    @IBAction func Btn0(_ sender: UIButton) {
      //元の数字に10かけて0を足して、答えに反映
        x = x * 10 + 0
        myEqu.text = String(x)
    }
//------------------------------------------------------------
    @IBAction func add(_ sender: UIButton) {
        //calculationの状態をチェック
        if calculation == "add" {
            y = y + x
            x = 0
        }
        else if calculation == "sub" {
            y = y - x
            x = 0
        }
        else if calculation == "mul" {
            y = y * x
            x = 0
        }
        else  if calculation == "div" {
            if x != 0 {
                y = y / x
                x = 0
            }
        }
        else if calculation == "none" {
            y = x
        }
        x = 0
        //計算結果をラベルに反映させる
        myEqu.text = String(y)
        calculation = "add"
    }
    @IBAction func sub(_ sender: UIButton) {
         //calculationの状態をチェック
        if calculation == "add" {
            y = y + x
            x = 0
        }
        else if calculation == "sub" {
            y = y - x
            x = 0
        }
        else if calculation == "mul" {
            y = y * x
            x = 0
        }
        else  if calculation == "div" {
            if x != 0 {
                y = y / x
                x = 0
            }
        }
        else if calculation == "none" {
            y = x
        }
        x = 0
        //計算結果をラベルに反映させる
        myEqu.text = String(y)
        calculation = "sub"
    }
    @IBAction func mul(_ sender: UIButton) {
         //calculationの状態をチェック
        if calculation == "add" {
            y = y + x
            x = 0
        }
        else if calculation == "sub" {
            y = y - x
            x = 0
        }
        else if calculation == "mul" {
            y = y * x
            x = 0
        }
        else  if calculation == "div" {
            if x != 0 {
                y = y / x
                x = 0
            }
        }
        else if calculation == "none" {
            y = x
        }
        x = 0
        //計算結果をラベルに反映させる
        myEqu.text = String(y)
        calculation = "mul"
    }
    @IBAction func div(_ sender: UIButton) {
         //calculationの状態をチェック
        if calculation == "add" {
            y = y + x
            x = 0
        }
        else if calculation == "sub" {
            y = y - x
            x = 0
        }
        else if calculation == "mul" {
            y = y * x
            x = 0
        }
        else  if calculation == "div" {
            if x != 0 {
                y = y / x
                x = 0
            }
        }
        else if calculation == "none" {
            y = x
        }
        x = 0
        //計算結果をラベルに反映させる
        myEqu.text = String(y)
        calculation = "div"
    }
//------------------------------------------------------------
    @IBAction func equ(_ sender: UIButton) {
         //calculationの状態をチェック
        if calculation == "add" {
            y = y + x
            x = 0
        }
        else if calculation == "sub" {
            y = y - x
            x = 0
        }
        else if calculation == "mul" {
            y = y * x
            x = 0
        }
        else  if calculation == "div" {
            if x != 0 {
                y = y / x
                x = 0
            }
        }
        else if calculation == "none" {
            y = x
        }
        myEqu.text = String(y)
        calculation = "none"
    }
//------------------------------------------------------------
    @IBAction func clear(_ sender: UIButton) {
        //変数・答えラベル・calculationの状態を初期に戻す
        x = 0
        y = 0
        myEqu.text = "0"
        calculation = "none"
    }