f = open('a.txt','rt',encoding='utf-8') 

f = open('a.txt','rb')  
f = open('a.txt','wb') 
f = open('a.txt','ab') 
#错误写法
f = open('a.txt','r') #未注明以b模式打开，这种写法是默认文本模式打开 
f = open('a.txt','rb'，encode = 'utf-8') #b模式打开，不能传入编码方式

f = open('a.txt','wb')
f.write('你哈'.encode('utf-8'))

with open('1.jpg', 'rb') as f: # 以只读模式打开文件
  data = f.read()       # 读取文件全部内容，并赋值给变量data
print(data)           # 打印变量，我们得到是b'\xff\xd8\xff\xe0\x00这种形式的结果
print(type(data))        # 变量的类型<class 'bytes'>

with open('1.jpg','rb') as f:
    data = f.read()
print(type(data))
print(data.decode('utf-8'))   #将读取的编码以utf-8标准解码
                 #图片文件编码方式不是utf-8，所以不能解码，程序报错

with open('db.txt', 'rb') as f: 
  data = f.read()
print(data)         # 打印出来的是一串二进制数
print(data.decode('utf-8')) # 把二进制数用utf-8标准解码
print(type(data))      # 可以在屏幕上显示人类能看懂的字符了

with open('db.txt', 'wb') as f:
  f.write('你好啊\n'.encode('utf -8'))

with open("db.txt", "r", encoding="utf-8") as f:  # 打开文件
  data = f.read()                # 读取文件全部内容
  data = data.replace("你好啊:", "======")    # 修改文件内容
  
with open("db.txt", "w", encoding="utf-8") as f:  # 以‘w'模式打开，清空文件
  f.write(data)                 # 把修改后的数据写入

import os # 引入os模块

with open('a.txt', 'r', encoding='utf-8') as read_f,     open('new.txt', 'w', encoding='utf-8') as new_f: # 同时打开文件
  for line in read_f:                  # 循环原文件内容
    if '你好啊' in line:
      line = line.replace('你好啊', '哈哈哈哈哈哈') # 替换源文件内容
    new_f.write(line)                # 把原文件循环出来的内容写入到新文件中，
    
os.remove('a.txt')                   # 调用OS模块功能删除原文件
os.rename('new.txt', 'a.txt')              # 重命名新文件