python-文件的创建与写入

1.利用内置函数获取文件对象

• 功能:
  • 生成文件对象，进行创建，读写操作
• 用法:
  • open(path,mode)
• 参数说明∶
  • path:文件路径
  • mode :操作模式
• 返回值:
  • 文件对象
• 举例:
  • f = open('d://a.txt' , ‘w')

2. 文件操作的模式之写入：

• 写入模式（“w”）：打开文件进行写入操作。如果文件已存在，则会覆盖原有内容；如果文件不存在，则会创建新文件。
• 注意：在写入模式下，如果文件已存在，原有内容将被清空。

3. 文件对象的操作方法之写入保存：

• write(str)：将字符串str写入文件。它返回写入的字符数。

  file.write("Hello, world!\n")

• writelines(lines)：将字符串列表lines中的每个字符串写入文件。它不会在字符串之间添加换行符。可以通过在每个字符串末尾添加换行符来实现换行。

  lines = ["This is line 1\n", "This is line 2\n", "This is line 3\n"]file.writelines(lines)

• close()：关闭文件，释放文件资源。在写入完成后，应该调用该方法关闭文件。

  file.close()

以下是一个示例代码，演示如何使用open函数获取文件对象并进行写入保存操作：

# 打开文件并获取文件对象file = open("example.txt", "w")# 写入单行文本file.write("Hello, world!\n")# 写入多行文本lines = ["This is line 1\n", "This is line 2\n", "This is line 3\n"]file.writelines(lines)# 关闭文件file.close()

在上述示例中，我们首先使用open函数以写入模式打开名为”example.txt”的文件，获取了文件对象file。然后，我们使用文件对象的write方法写入了单行文本和writelines方法写入了多行文本。最后，我们调用了close方法关闭文件。

请确保在写入完成后调用close方法来关闭文件，以释放文件资源和确保写入的数据被保存。

操作完成后，必须使用close方法！
避坑指南：
#当打开的文件中有中文的时候，需要设置打开的编码格式为utf-8或gbk，视打开的原文件编码格式而定

实战

在这里插入代码片# coding:utf-8# @Author: DX# @Time: 2023/5/29# @File: package_open.pyimport osdef create_package(path):if os.path.exists(path):raise Exception('%s已经存在,不可创建' % path)os.makedirs(path)init_path = os.path.join(path, '__init__.py')f = open(init_path, 'w', encoding='utf-8')f.write('# coding: utf-8\n')f.close()class Open(object):def __init__(self, path, mode='w', is_return=True):self.path = pathself.mode = modeself.is_return = is_returndef write(self, message):f = open(self.path, mode=self.mode, encoding='utf-8')try:if self.is_return and message.endswith('\n'):message = '%s\n' % messagef.write(message)except Exception as e:print(e)finally:f.close()def read(self, is_strip=True):result = []with open(self.path, mode=self.mode, encoding='utf-8') as f:data = f.readlines()for line in data:if is_strip:temp = line.strip()if temp != '':result.append(temp)else:if line != '':result.append(line)return resultif __name__ == '__main__':current_path = os.getcwd()# path = os.path.join(current_path, 'test2')# create_package(path)open_path = os.path.join(current_path, 'b.txt')o = open('package_datetime.py', mode='r', encoding='utf-8')# o = os.write('你好~')data1 = o.read()print(data1)

输出结果（遍历了package_datetime.py中的内容）：

# coding:utf-8# Time: 2023/5/28# @Author: Dx# @File:package_datetime.pyfrom datetime import datetimefrom datetime import timedeltanow = datetime.now()print(now, type(now))now_str = now.strftime('%Y-%m-%d %H:%M:%S')print(now_str, type(now_str))now_obj = datetime.strptime(now_str, '%Y-%m-%d %H:%M:%S')print(now_obj, type(now_obj))print('===========================================')three_days = timedelta(days=3)# 这个时间间隔是三天，可以代表三天前或三天后的范围after_three_days = three_days + nowprint(after_three_days)after_three_days_str = after_three_days.strftime('%Y/%m/%d %H:%M:%S:%f')print(after_three_days_str, type(after_three_days_str))after_three_days_obj = datetime.strptime(after_three_days_str, '%Y/%m/%d %H:%M:%S:%f')print(after_three_days_obj, type(after_three_days_obj))print('===========================================')before_three_days = now - three_daysprint(before_three_days)before_three_days_str = before_three_days.strftime('%Y/%m/%d %H:%M:%S:%f')print(before_three_days_str, type(before_three_days_str), '=================')before_three_days_obj = datetime.strptime(before_three_days_str, '%Y/%m/%d %H:%M:%S:%f')print(before_three_days_obj, type(before_three_days_obj))print('===========================================')one_hour = timedelta(hours=1)after_one_hour = now + one_hourafter_one_hour_str = after_one_hour.strftime('%H:%M:%S')print(after_one_hour_str)after_one_hour_obj = datetime.strptime(after_one_hour_str, '%H:%M:%S')print(after_one_hour_obj, type(after_one_hour_obj))# default_str = '2023 5 28 abc'# default_obj = datetime.strptime(default_str, '%Y %m %d')进程已结束,退出代码0

package_datetime.py

# coding:utf-8# Time: 2023/5/28# @Author: Dx# @File:package_datetime.pyfrom datetime import datetimefrom datetime import timedeltanow = datetime.now()print(now, type(now))now_str = now.strftime('%Y-%m-%d %H:%M:%S')print(now_str, type(now_str))now_obj = datetime.strptime(now_str, '%Y-%m-%d %H:%M:%S')print(now_obj, type(now_obj))print('===========================================')three_days = timedelta(days=3)# 这个时间间隔是三天，可以代表三天前或三天后的范围after_three_days = three_days + nowprint(after_three_days)after_three_days_str = after_three_days.strftime('%Y/%m/%d %H:%M:%S:%f')print(after_three_days_str, type(after_three_days_str))after_three_days_obj = datetime.strptime(after_three_days_str, '%Y/%m/%d %H:%M:%S:%f')print(after_three_days_obj, type(after_three_days_obj))print('===========================================')before_three_days = now - three_daysprint(before_three_days)before_three_days_str = before_three_days.strftime('%Y/%m/%d %H:%M:%S:%f')print(before_three_days_str, type(before_three_days_str), '=================')before_three_days_obj = datetime.strptime(before_three_days_str, '%Y/%m/%d %H:%M:%S:%f')print(before_three_days_obj, type(before_three_days_obj))print('===========================================')one_hour = timedelta(hours=1)after_one_hour = now + one_hourafter_one_hour_str = after_one_hour.strftime('%H:%M:%S')print(after_one_hour_str)after_one_hour_obj = datetime.strptime(after_one_hour_str, '%H:%M:%S')print(after_one_hour_obj, type(after_one_hour_obj))# default_str = '2023 5 28 abc'# default_obj = datetime.strptime(default_str, '%Y %m %d')