Python---file operations

first, the document operation process
1. Open the file, get the file handle and assign a value to a variable
2. Manipulating files with file handles
3. Close the file


Second, the file open mode

F = open ("File_test", "R",encoding =  "Utf-8")      #打开文件, "read mode", read Only, Get the file handle and assign a value to a variable print (F.read ())                        #读文件所有内容, after reading the file cursor jumps to the end, the file is used with caution f.close () f1 = open ("File _test "," W ", encoding=" Utf-8 ")       #写模式, creates a new File_test file and writes F1.write ("-------------") F1.close () F2 = open ("File_test", "a", encoding= "Utf-8")       #追加模式, appended at the end of the original file, New F2.write ("-------------") f2.close ("F3  = open") ("File_test", "r+", encoding= "Utf-8") without the original file       #读写模式, written at the end of the original file content appended, no original file is new print (F3.readline ())                     #按行读print (F3.readline ()) print (F3.readline ())                   # Print the first three lines, this time the cursor moves to the third row position print (f3.tell ())                       #打印光标位置f3. Write ("--------------")                  #但是写入还是文件内容最后写入f3. Close () F4  = open ("File_test", "w+", encoding= "Utf-8")      #写读模式, as long as "write in front" will build a new file in writing f4.write ("----------------------\ n") F4.write ("----------------------\ n") f4.write ("----------------------\ n") F4.seek (Ten)                           #光标移动到10的位置f4. Write ("test4")                       #再写入会将原内容覆盖f4. Seek (0)                          # Move the cursor to the beginning of the position print (F4.read ()) F4.close () #输出 #----------ni hao -----#----------------------#----------------------F5  = open ("File_ Test "," A + ", encoding=" Utf-8 ")      #追加读模式, appended at the end of the original file, without the original file New F5.write ("----------------------\ n ") f5.write ("----------------------\ n ") f5.write ("----------------------\ n ") F5.seek (Ten)                           #光标移动到10的位置f5. Write ("Test5")                       #再写入会在文件内容最后写入f5. Seek (0) print (F5.read ()) F5.close () f6   = open ("File_test", "RB")                    #以二进制文件格式读这个文件print (F6.readline ()) print (F6.readline ()) print (F6.readline ()) F6.close () F7  = open ("File_test", "AB")                    #以二进制文件格式追加这个文件f7. Write ("-------------------\ n". Encode ())          #encode   Converts the str character to Bytesf7.write ("-------------------\ n". Encode ()) f7.write ("-------------------\ n". Encode ()) F7.close () F8  = open ("File_test", "WB")                    #以二进制文件格式写这个文件f8. Write ("-------------------\ n". Encode ())         #encode   Converts the str character to Bytesf8.write ("-------------------\ n". Encode () ) f8.write ("-------------------\ n". Encode ()) F8.close () #注: Also Ru or r+u mode, "U" means that when reading, the  \r \n \r\ can be n Automatic conversion to  \n  (in conjunction with  r  or  r+  mode)

Iii. Circulation of documents

#按行循环 and replace line fifth with F = open ("File_test", "R", encoding= "Utf-8") Count = 0for lines in F:count + = 1 if count = = 5:pri NT ("----Split line----") Continue print (Line.strip ()) #strip是去除行首行尾的空格符和换行符f. Close () #f. Readli NES () #切记用f. ReadLines is to convert the file to a list first, if the file is too large to consume too much memory

Iv. Modification of documents

#打开一个文件, modified to write to a new file F = open ("File_test", "R", encoding= "Utf-8") f_new = open ("File_new", "W", encoding= "Utf-8") for line In F: #按行取出, each line is a string of strings if "Fengxiaoli" in line:line = Line.replace ("Fengxiaoli", "F Engxiaoli ") #对字符串进行操作, J f_new.write (line) F.close () F_new.close ()

Five, flush method

f = open ("File_test", "W", encoding= "Utf-8") f.write ("hello\n") f.write ("hello\n") f.write ("hello\n") F.flush () # When writing to a file, there is a cache that reaches a time and writes to the file at once. Flush Flushing executes immediately if the power outage may not have been successfully written

Vi. with statements

#with语句作用, in order to avoid opening the file after forgetting to close with open ("File_test", "R", encoding= "Utf-8") as f: #类似于f = open ("File_test", "R", encoding= "u Tf-8 ") with open (" File_test "," R ", encoding=" Utf-8 ") as F, \ #还可以同时打开多个文件 open (" File_test2 "," R ", encoding=" Utf-8 ") as F2:

Vii. Other operations

F = open ("File_test", "R", encoding= "Utf-8") print (F.tell ())                 #打印光标位置, Count print by character (F.readline ())             #按行读print (F.read)               #按字符读print (F.tell ()) f.seek (0)                      #把光标回到开头f. Seek ()                     #把光标移动到12个字符的位置print (F.readline ()) Print ( f.encoding)             #打印文件编码print (F.isatty ())              #判断文件是否是终端设备, return Ture or falseprint ( F.seekable ())           #判断是否能移动文件光标, return ture or falseprint (F.readable ())    &Nbsp;      #判断文件是否可读print (f.writable ())            #判断文件是否可写 # f  = open ("File_test", "a", encoding= "Utf-8") # f.truncate ()         #从头开始截取多少字符

Python---file operations