MainActivityOp.kt

var operator = "*"
    var oldCount=""
    var newOperator=true
//operator butonlarımız
    fun btn_Operator(view: View) {
        var btn_Select= view as Button
        when(btn_Select.id){
            btn_Div.id->{
                operator="/"
            }
            btn_Mul.id->{
                operator="*"
            }
            btn_Sub.id->{
                operator="-"
            }
            btn_Sum.id->{
                operator="+"
            }
        }
        oldCount=dataView.text.toString()
        newOperator=true
    }