python - 如何在 Python 中更新变量

Question

我如何更新变量 constanta 的余额

def menu():
   balance = float(100.0)
   print (" 1.Balance 2.Draw ")
   ask = ('choose')

   if (ask == '1'):
       print ("Your Balance is {0}".format, balance)
       ask2 = input('do you want go back to menu ?')

       if (ask2 == 'y'):
          menu()
       else:
          sys.exit()

   elif (ask == '2'):
       draw = input("How Much : ")
       new_balance = (balance - draw)
       balance = new_balance
       print (balance)
       ask2 = input('do you want go back to menu ?')

       if (ask2 == 'y'):
          menu()
       else:
          sys.exit()

所以当我的第一个输入是 1输出是 100.0 ，然后我返回菜单，第二个输入我选择 2 和 draw输入 50所以 new_balance是50 .然后我回到menu()然后选择输入1但是 balance 变量仍然是 100.0 .

如何更新变量直到 balance = 0

Answer 1

因为每当您进入 menu 功能时，您都将 100.0 分配给 balance 变量。为了解决这个问题，您可以创建一个 balance 全局变量，也可以使用 while 循环。

 def menu():
        balance = float(100.0)
        while true:
            print (" 1.Balance 2.Draw ")
            ask = input('choose')

            if (ask == '1'):
                print ("Your Balance is {0}".format, balance)
                ask2 = input("do you want go back to menu ?")

                if (ask2 == 'y'):
                    continue
                else:
                    break

            elif (ask == '2'):
                draw = input("How Much : ")
                balance = (balance - draw)
                print (balance)
                if(balance == 0):
                    print("Your balance is 0")
                    break
                ask2 = input("do you want go back to menu ?")

                if (ask2 == 'y'):
                    continue
                else:
                    break