如何解决需要更正这个计算器程序
无法获得用于计算的第二个值 (var b)。
在这个计算器程序中,我从 display.text 中获得了第一个值 (var a) 并清除了 display.text。然后获得了第二个值 (var b) 用于加法/减法,第二个值仍然分配给 var a 和出现错误
意外地发现值 b 为 nil
import UIKit
class ViewController: UIViewController {
@IBOutlet weak var display: UITextField!
@IBOutlet weak var nine: UIButton!
@IBOutlet weak var eight: UIButton!
@IBOutlet weak var seven: UIButton!
@IBOutlet weak var six: UIButton!
@IBOutlet weak var five: UIButton!
@IBOutlet weak var four: UIButton!
@IBOutlet weak var clear: UIButton!
@IBOutlet weak var result: UIButton!
@IBOutlet weak var add: UIButton!
@IBOutlet weak var subtract: UIButton!
@IBOutlet weak var multiply: UIButton!
@IBOutlet weak var three: UIButton!
@IBOutlet weak var two: UIButton!
@IBOutlet weak var one: UIButton!
var res : Int = 0
var a : Int = 0
var b : Int = 0
var actionBtn : Int = 0
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
@IBAction func numbers(_ sender: Any) {
display.text = display.text! + String((sender as AnyObject).tag)
print("displtxt = ",display.text)
}
@IBAction func functionality(_ sender: Any) {
actionBtn = (sender as AnyObject).tag
a = Int(display.text!)!
print("a = ",a)
display.text = ""
}
@IBAction func clearDisplay(_ sender: Any) {
display.text = ""
}
@IBAction func results(_ sender: Any) {
b = Int(display.text!)!
switch actionBtn {
case 10:
print("b = ",b)
res = a*b
print("res = ",res)
case 11:
res = a-b
case 12:
res = a+b
default:
display.text = ""
}
}
}
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