Question

好吧，我是python的新手，我正在学校上课，我对此感到困惑。我们正在编写一个程序/脚本来计算买卖股票的交易，由于某种原因，我无法获得随时间累积的“余额”变量，并从买卖股票中扣除并增加。这是代码。任何输入都会很棒^。^

def main():

    #Below is the variables used in the context

    balance = float(input("Starting cash amount? "))
    numtrades = int(input("Number of trades for today?"))
    print('You do not own any shares, but have', balance, 'in cash')
    buy = 0
    sell = 0
    price_per_share = 0
    transaction_amount = 0
    transaction_amount_buy = 0
    transaction_amount_sell = 0


    #Below is the prompt for the first transaction, which requires a buy

    num_shares = int(input('Number of shares to buy?'))
    price_per_share = float(input('Price per share?'))
    print(num_shares, "shares for $",price_per_share, "per share cost $",price_per_share * num_shares)
    buy = buy + num_shares
    transaction_amount_buy = transaction_amount_buy + (num_shares * price_per_share)
    print("Currently holding", buy, "and have $", balance - transaction_amount_buy , "in cash")


    if balance < transaction_amount :

            print('You do not have sufficient funds to purchase', num_shares, 'for $', price_per_share, 'per share.')
            print('Your current balance is', balance, ', but', num_shares,' x ', price_per_share,' = ', num_shares * price_per_share)
            print("Currently holding", buy, "and have $", balance - transaction_amount , "in cash")




    #Below is the loop counter for each trade, along with if statements for buy/sell


    for i in range(numtrades):
        print('Trade number', (i + 2), end = "")
        action = input(' (buy/sell)?')
        if action == 'buy':
            num_shares = int(input('Number of shares to buy?'))
        if action == 'sell':
            num_shares = int(input('Number of shares to sell?'))
        price_per_share = float(input('Price per share?'))
        print('Transaction', (i+2))
        print('Transaction type is', action)


        if action == 'buy':
            print(num_shares, "shares for $",price_per_share, "per share cost $",price_per_share * num_shares)
            buy = buy + num_shares
            transaction_amount_buy = transaction_amount_buy + (num_shares * price_per_share)

        if action == 'sell':
            print(num_shares, 'shares for $',price_per_share, 'per share worth $',price_per_share * num_shares)
            sell = sell + num_shares
            transaction_amount_sell = transaction_amount_sell + (num_shares * price_per_share)

        transaction_amount = transaction_amount_buy - transaction_amount_sell

        if balance < transaction_amount :

            print('You do not have sufficient funds to purchase', num_shares, 'for $', price_per_share, 'per share.')
            print('Your current balance is', balance - transaction_amount, ', but', num_shares,' x ', price_per_share,' = ', num_shares * price_per_share)
            print("Currently holding", buy, "and have $", balance - transaction_amount , "in cash")


        if balance > transaction_amount :
            print("Currently holding", buy, "and have $", balance - transaction_amount , "in cash")

 main()

Answer 1

您打印差异balance - transaction_amount，但您从未将此值设置为balance变量。差不多，你做的事情与：

相同

>>> cupcakes = 5
>>> print("I ate one cupcake, now I have", cupcakes - 1, "cupcakes")
I ate one cupcake, now I have 4 cupcakes
>>> print(cupcakes)
5 # We never modified the variable cupcakes

在打印报表之前，请执行balance = balance - transaction_amount（或balance -= transaction_amount），然后在打印功能中添加balance。

Answer 2

transaction_amount_buy = transaction_amount_buy + (num_shares * price_per_share)
balance = balance - transaction_amount_buy
print("Currently holding", buy, "and have $", balance , "in cash")

这应该让第一部分工作，现在其余部分应该遵循......

Answer 3

我建议您将此问题解决为一系列较小的问题。通过创建仅处理较小问题的函数来做到这一点。在尝试将它们全部连接在一起之前，让每个函数都有效。

示例：无论您是否购买了东西，都有余额。您选择购买或出售。你买什么或卖什么？如果你卖的话，你拥有它吗？如果没有，那可以吗？是不同的卖（卖空）你不拥有的东西。

所以保持简单，开始吧。假设您只购买或出售香蕉。购买100种不同于销售100种香蕉的香蕉？如果您处理的是大于0的数字并且卖出的数字小于零，则不是真的。

所以你有（现金）余额。当您“购买”时，您将退还成本。余额应按成本递减。如果你卖掉，余额应该增加成本。

嗯..你能卖掉你不拥有的东西吗？您似乎不仅需要跟踪您的余额，还需要跟踪您购买或出售的商品中的“头寸”。

如果您的销售量超过您自己的价格，或者购买价格超过您的余额的香蕉，您需要有办法处理这些问题。

变量不随时间积累？

3 个答案: