White learning day6 ------ file operations

Chapter IV file copy operation &

4.1 File Operations

4.1.1 Create a file

1：
f1 =open('a.txt',mode='w',encoding='utf-8')

2：
with open('a.txt',mode='w',encoding='utf-8') as f1 :
 #  自动缩进 编写文件 自己关闭文件

4.1.2 open mode

• w write will clear the original content of the document
• r 读 read
• Additional file a written final
  
• w + / r + / a + read and write operations
• wb / rb / ab with a binary operation resumable
• w+b / r+b / a+b

4.1.3 Close File

f1 =open('a.txt',mode='w',encoding='utf-8')

f1.close()   #  每个文件打开操作后 关闭

4.1.4 Read / Write / Append

• w write file

  # -------------------写，但覆盖原来文件-------------------
  
  f = open('文件',mode='w',encoding=('utf-8'))
  f.write('吃葡萄不吐葡萄皮，不吃葡萄倒吐葡萄皮')
  f.close()
  

• r read the contents of the file

  # --------------读 r------------------------------------
  f = open('文件',mode='r',encoding=('utf-8'))
  s=f.read()
  print(s)
  f.close()
  
  #------也可以循环的读取文件
  with open('文件','r',encoding='utf-8')as f1 :
      for i in f1 :
          print(i)
  
  

• Additional file a final

  f= open('文件',mode='a',encoding='utf-8')
  f.write("\nales，大王牛逼")#\n换行
  
  f.close()

• Read and write operations

  • w+

    with open('文件',mode='r+',encoding='utf-8') as f1 :
        f1.write('alex sb')
        f1.seek(0)   #  移动光标位置  不移动读的空白
        s =f1.read()
        print(s)

  • r+

    with open('文件',mode='r+',encoding='utf-8') as f1 :
        s =f1.read()
        f1.write('alex sb')   # 因为读完后 光标在最后写入内容，不会覆盖原来的内容
        print(s)
    

  • a+

    with open('文件',mode='a+',encoding='utf-8') as f1 :
        f1.write('alex sb')
        f1.seek(0)
        s =f1.read()
        print(s)

4.1.5 File Operations

• File modification

  #  只能读取到内存再修改 ，直接在硬盘上只能对应的字节
  n = open('文件','r+',encoding='utf-8')
  r = n.read()
  read =r.replace('王豪','哈哈')
  n.seek(0)
  n.write(read)
  n.close()
  
  
  import os  
  import time    #时间模块
  with open('文件',mode='r',encoding='utf-8')as f1,\
      open('文件_副本',mode='w',encoding='utf-8')as f2 :
      for line in f1 :
          line=line.replace('alse','sb')
          f2.write(line)
  time.sleep(3)
  os.remove('文件')#删除
  time.sleep(3)
  os.rename('文件_副本','文件')#重新命名alse，大王牛逼
  

• seek

  Move the cursor to a position corresponding byte encoded according to the written Ann

  # 文件的内容是      ‘哈哈alex sbalex sbalex sb’
  with open('文件',mode='r',encoding='utf-8') as f1 :
      f1.seek(7)   
      s = f1.read(1)
      print(s)   # l
  
      f1.seek(3)
      s = f1,read(1)
      print(s)  #哈
  
  
  
  特殊情况  a+
  with open('文件',mode='a+',encoding='utf-8') as f1 :
      f1.seek(0)
      f1.write('alex sb')   #光标移动到开头，但追加只在最后写
      f1.seek(0)
      s =f1.read()
      print(s)

• read

  You can specify the number of read content (characters)

  # 文件的内容是      ‘哈哈alex sbalex sbalex sb’
  with open('文件',mode='r',encoding='utf-8') as f1 :
  
      s = f1.read(1)
      print(s)   # 哈

• tell return position of the cursor

  with open('文件',mode='r',encoding='utf-8') as f1 :
      f1.seek(7)
      s = f1.tell()
      print(s)

4.1.6 HTTP

• wb / rb / ab

  f1 = open('文件',mode='wb')
  n = '王豪傻逼，寂寞了'
  n = n.encode('utf-8')    #   忘了 看3.3.5
  f1.write(n)
  f1.close()