计算 a.txt 文件中的行数，得到预期结果的两倍

Question

I'm trying to write a very basic script that will take a input file name and simply count the number of lines in the file, and print it to CMD. I am getting double the number of lines that are actually in the file when I run it though.

import sys


filename = sys.argv[-1]
with open(filename,) as f:
    LineCount = len(f.readlines())
print(LineCount)
input("Press Enter to close...")

The text file is 208 lines long, I am getting 417 back. Here is what the file looks like. It just repeats from here on out.

Asset Name              In Point            Description 
Zach And Jenv4          00:00:13:11                         
Zach And Jenv4          00:00:14:54                         
Zach And Jenv4          00:00:16:37                         
Zach And Jenv4          00:00:18:20                         
Zach And Jenv4          00:00:20:03                         
Zach And Jenv4          00:00:21:45                         
Zach And Jenv4          00:00:23:28                         
Zach And Jenv4          00:00:25:11                         
Zach And Jenv4          00:00:26:54                         
Zach And Jenv4          00:00:28:36                         
Zach And Jenv4          00:00:30:20                         
Zach And Jenv4          00:00:32:03                         
Zach And Jenv4          00:00:33:45                         
Zach And Jenv4          00:00:35:28                         
Zach And Jenv4          00:00:37:11                         
Zach And Jenv4          00:00:38:54                         
Zach And Jenv4          00:00:40:37                         
Zach And Jenv4          00:00:42:20                         
Zach And Jenv4          00:00:44:03                         
Zach And Jenv4          00:00:45:44                         
Zach And Jenv4          00:00:47:28                         
Zach And Jenv4          00:00:49:11                         
Zach And Jenv4          00:00:50:54                         

Answer 1

Here's a likely explanation, but OP should look at f.readlines() content to be sure.

The file has \r\r\n line termination and the default for open is to translate \r , \n , and \r\n each to a newline when reading, so \r\r\n gets translated to \n\n . One way to generate a file with these line terminations is to use Python's csv.writer without the documented newlines='' parameter when opening the file for writing on a Windows OS:

import csv

# Create "bad" file
with open('test.csv','w') as f:  # should have newline='' as a parameter as well
    r = csv.writer(f)
    r.writerow(['a','b','c'])
    r.writerow([1,2,3])
    r.writerow([4,5,6])

# Read file as OP did
with open('test.csv') as f:
    data = f.readlines()

print(len(data))
print(data)

Output:

6
['a,b,c\n', '\n', '1,2,3\n', '\n', '4,5,6\n', '\n']

With newline='' parameter added to the open :

3
['a,b,c\n', '1,2,3\n', '4,5,6\n']

Open the CSV file in Excel, Notepad or Notepad++ and you'll see the same double-newline issue, but dumping from the command line doesn't:

C:\>type test.csv
a,b,c
1,2,3
4,5,6

A hex editor will show the \r\r\n ( 0D 0D 0A in hexadecimal):