### Python 实现货币转换 示例代码 以下是基于提供的参考资料以及专业知识编写的 Python 货币转换程序示例： #### 功能描述 该程序能够接受用户输入的金额和对应的货币单位（如 USD 或 CNY），并将其转换为目标货币。假设汇率固定为 1 USD = 7.0 CNY。 ```python def currency_converter(amount, source_currency, target_currency): # 定义固定的汇率 exchange_rates = { 'USD_to_CNY': 7.0, 'CNY_to_USD': 1 / 7.0 } if source_currency == 'USD' and target_currency == 'CNY': converted_amount = amount * exchange_rates['USD_to_CNY'] return f"{amount} {source_currency} is equal to {converted_amount:.2f} {target_currency}"[^1] elif source_currency == 'CNY' and target_currency == 'USD': converted_amount = amount * exchange_rates['CNY_to_USD'] return f"{amount} {source_currency} is equal to {converted_amount:.2f} {target_currency}" else: return "Unsupported currency conversion" # 用户输入部分 if __name__ == "__main__": try: user_input = input("Enter the amount with currency (e.g., USD20): ") source_currency = user_input[:3].upper() amount = float(user_input[3:]) if source_currency == 'USD': result = currency_converter(amount, 'USD', 'CNY') elif source_currency == 'CNY': result = currency_converter(amount, 'CNY', 'USD') else: result = "Invalid source currency" print(result) except ValueError: print("Please enter a valid number.") ``` #### 说明 上述代码实现了基本的货币转换功能，支持从 USD 到 CNY 和从 CNY 到 USD 的双向转换。它还包含了简单的错误处理机制，用于捕获非法输入的情况[^2]。 --- ### 进阶扩展：动态汇率获取 如果需要更灵活的功能，可以通过 API 获取实时汇率数据。以下是一个使用 `requests` 库调取外部 API 并完成货币转换的例子： ```python import requests def fetch_exchange_rate(base_currency, target_currency): url = f"https://api.exchangerate-api.com/v4/latest/{base_currency}" response = requests.get(url) data = response.json() rate = data['rates'][target_currency] return rate def dynamic_currency_converter(amount, base_currency, target_currency): rate = fetch_exchange_rate(base_currency, target_currency) converted_amount = amount * rate return f"{amount} {base_currency} is approximately {converted_amount:.2f} {target_currency}" if __name__ == "__main__": try: user_input = input("Enter the amount with currency (e.g., USD20): ") base_currency = user_input[:3].upper() amount = float(user_input[3:]) target_currency = input(f"Convert from {base_currency} to which currency? ").upper() result = dynamic_currency_converter(amount, base_currency, target_currency) print(result) except Exception as e: print("An error occurred:", str(e)) ``` 此版本利用了第三方免费 API 来提供最新的汇率信息，从而增强了程序的实际应用价值[^3]。 ---