Python: File operations

Open File

Action File 1 When you open a file, you need to specify the file path and open with open mode: R: Read Only W: Write only A: Append "+" indicates that a file can be read and written r+: Read-write w+: Read A +: with a

U "means the \ r \ n \ r \ \ \ \ \ \ \ \ \ \ \ \ r/N (r+ mode) can be converted automatically when reading

• RU
• R+u

"B" means processing binary files (e.g. FTP send upload ISO image file, Linux can be ignored, Windows process binary file should be labeled)

• Rb
• Wb
• Ab

  1f = open ('Test.log','r+', encoding='Utf-8')2F.write ('Sdhgrbfds in SAF')3 Print(F.tell ())#View the current pointer position, in characters4F.seek (4)#Specifies the current pointer position, in bytes5 Print(F.read (4))6F.truncate ()#read the data before the pointer7 Print(F.tell ())8F.close ()

  View Code

  Second: Common file operations

  f = open (' Data ', ' R ')  #以只读形式打开 (default is read-only)

  f = open (' F.txt ', encoding= ' latin-1 ')   #python3.0 Unicode file

  string = F.read ()      #把文件读入一个字符串中

  String = F.read (N)     #读取指针后的N个字节

  string = F.readline ()  #读取下一行, including end-of-line identifiers

  Alist = F.readlines ()  #读取整个文件到字符串列表

  F.write ()              #将字符串写入文件

  F.writelines ()         #将列表内所有字符串写入文件

  F.close ()              #手动关闭

  F.flush ()              #把输出缓冲区刷到硬盘中

  F.seek (N)              #将文件指针移到N处, in bytes

  For line in open (' Data '):  

      Print (line)        #文件迭代器将文件一行行读出

  Open (' F.txt ', ' R '). Read () #read all @ ance into string

  Three: Storing and parsing Python objects in a file

  X, y, z = 41,42,43
  s = ' spam '
  D = {' A ': 1, ' B ': 2}   #字典对象
  L = [' A ', ' B ', ' C ']   #列表
  f = open (' F.txt ', ' W ')
  F.write (s + ' \ n ')
  F.write ('%s,%s,%s\n '% (x, y, z))
  F.write (str (D))
  F.write (' \ n ')
  F.write (str (L))
  F.close ()
  Print (Open (' f.txt '). Read ()) #将文件内容输出
  #从文件中取出数据, and judge its type
  ‘‘‘
  A = Fi.readline ()
  b = Fi.readline ()
  c = Fi.readline ()
  D = Fi.readline ()
  
  Print (A,b,c,d,type (a), type (b), type (c), type (d))
  ‘‘‘
  # Extract data from file and convert to pre-storage type
  fi = open (' F.txt ')
  A = Fi.readline (). Rstrip ()    #rstrip () Remove line break
  Print (A,type (a))
  b = Fi.readline (). Rstrip (). Split (', ')  #字符串的split () method, writes a delimiter in parentheses, and divides the string into a list.
  Print (B,type (b))
  c = Fi.readline ()
  c = eval (c)   #调用内置函数eval () to convert the string into executable python code.
  Print (C,type (c), type (c))
  D = Fi.readline ()
  D = eval (d)
  Print (D,type (d), type (d))

Python: File operations