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Nikolay
Asked:2022-08-09 22:44:40 +0800 CST2022-08-09 22:44:40 +0800 CST

Python sys 模块，运行 IndexError 时出错：列表索引超出范围

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from datetime import datetime

import requests

API_KEY = "..."


def convert_currency(src, dst, amount):
    """converts `amount` from the `src` currency to `dst` using the free account"""
    url = f"http://data.fixer.io/api/latest?access_key={API_KEY}&symbols={src},{dst}&format=1"
    data = requests.get(url).json()
    if data["success"]:
        # request successful
        rates = data["rates"]
        # since we have the rate for our currency to src and dst, we can get exchange rate between both
        # using below calculation
        exchange_rate = 1 / rates[src] * rates[dst]
        last_updated_datetime = datetime.fromtimestamp(data["timestamp"])
        return last_updated_datetime, exchange_rate * amount


    if __name__ == "__main__":
      import sys

    source_currency = sys.argv[1]
    destination_currency = sys.argv[2]
    amount = float(sys.argv[3])

    last_updated_datetime, exchange_rate = convert_currency(source_currency, destination_currency, amount)
    # upgraded account, uncomment if you have one
    # last_updated_datetime, exchange_rate = convert_currency source_currency, destination_currency, amount)
    print("Last updated datetime:", last_updated_datetime)
    print(f"{amount} {source_currency} = {exchange_rate} {destination_currency}")

大家好。我试图处理 sys 模块以制作 CLI 界面，但是当我启动它时，它会出错。不要告诉我到底是什么问题？提前致谢。

source_currency = sys.argv[1]
IndexError: list index out of range
python python-3.x

1 个回答

  1. Best Answer

    问题是您错误地调用了您的应用程序。

    sys.argv包含您在命令行上传递给应用程序的参数。也就是说，如果您使用以下命令启动应用程序：

    python app.py 1 2 3

    然后 insys.argv将是一个列表['app.py', '1', '2', '3']。index out of range通常意味着列表中该索引处没有元素。在您的情况下，这意味着您没有按照此代码的预期在命令行上传递参数。

    要修复，只需在启动时传递所需的参数。

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