如何通过从python中的另一个文本文件中查找位置来打印文件中的行？

Question

This is my code for getting lines from a file by seeking a position using f.seek() method but I am getting a wrong output. it is printing from middle of the first line. can u help me to solve this please?

f=open(r"sample_text_file","r")
last_pos=int(f.read())
f1=open(r"C:\Users\ddadi\Documents\project2\check\log_file3.log","r")
f1.seek(last_pos)
for i in f1:
    print i
    last_position=f1.tell()
    with open('sample_text.txt', 'a') as handle:
        handle.write(str(last_position))

sample_text file contains the file pointer offset which is returned by f1.tell()

Answer 1

If it's printing from the middle of a line that's almost certainly because your offset is wrong. You don't explain how you came by the magic number you use as an argument to seek , and without that information it's difficult to help more precisely.

One thing is, however, rather important. It's not a very good idea to use seek on a file that is open in text mode (the default in Python). Try using open(..., 'rb') and see if the process becomes a little more predictable. It sounds as though you may have got the offset by counting characters after reading in text mode, but good old Windows includes carriage return characters in text files, which are removed by the Python I/O routines before your program sees the text.