def stock_trading(stock, budget):

# 初始化仓位 
position = 0 

# 根据股票价格和预算，计算可买入的股数量 
stock_amount = int(budget/stock)  

while True:  

    print("当前投资额为：{}".format(position*stock))  

    # 用户选择是否买入或者卖出股票 
    decision = input("请问你要买入还是卖出？（buy/sell）")  

    if decision == "buy":  

        if budget >= stock:  

            position += stock_amount  

            budget -= stock * stock_amount 

            print("您已成功买入{}手{}股票".format(stock_amount, stock))  

        else:  

            print("对不起，您的预算不够") 
             break; 
              else:       # 卖出情况      if position > 0:         position -= stock_amount         budget += stock * stock_amount         print("您已成功卖出{}手{}股票".format(stock_amount,stock))      else :         print("对不起，您目前无可卖出的仓位")