CSV文件追加时出现空行问题（禁止使用Pandas）

问题原因 #

你的代码里用csv.writer写入文件时，未指定newline=''参数，导致Windows系统下文件默认换行处理与csv模块的换行逻辑叠加，产生额外空行。此外代码还存在导入错误：仅导入了csv.writer，却直接调用csv.reader，会触发NameError，需补上reader的导入。

修正方案 #

1. 导入csv模块的writer和reader，或直接导入整个csv模块
2. 打开写入目标文件时添加newline=''参数，让csv模块自行处理换行逻辑
3. 优化异常处理，避免捕获无关异常；添加返回逻辑，防止文件不存在时后续代码报错

修正后的完整代码 #

from csv import writer, reader

def ImportFunction():
    which_file = input("Which file would you like to import?")
    
    # 验证用户指定文件是否存在
    try:
        with open(which_file, 'r') as file:
            user_file = file.read()
            print(user_file)
    except FileNotFoundError:
        print("Sorry the user file can't be found. Please try again.")
        return  # 文件不存在时直接返回，避免后续执行出错
    
    # 处理transaction_ledger.csv
    try:
        with open('transaction_ledger.csv', 'r') as file:
            file_content_transaction_ledger = file.read()
            print(file_content_transaction_ledger)
    except FileNotFoundError:
        # 文件不存在时创建并写入内容
        with open(which_file, 'r') as old_file:
            reader_obj = reader(old_file)
            
            # 关键：添加newline=''参数解决空行问题
            with open('transaction_ledger.csv', 'w', newline='') as new_file:
                writer_obj = writer(new_file, delimiter=",")
                for data in reader_obj:
                    writer_obj.writerow(data)
        print("New file created and filled in with old file data")  

ImportFunction()

with open('transaction_ledger.csv', 'r') as file:
    file_content_transaction_ledger = file.read()
    print(file_content_transaction_ledger)

说明 #

• newline=''参数让csv.writer根据系统自动适配换行符，避免双重换行产生空行
• 将裸except改为FileNotFoundError，精准捕获文件不存在的异常，便于调试
• 补充reader导入，解决原代码潜在的NameError问题

内容的提问来源于stack exchange，提问作者Jorge Daniel Atuesta