CODEWITHSUNDEEP
python
Uckel
Uckel

Reputation: 13

Read file line by line and add something new to each one

I know something similar has been asked before but I'm new to python and I can not find a solution for my problem:

What I want to do is this: 1. Open a file and read it line by line. (I already managed to do that) 2. Add something new after each line. (I want to combine this with an if statement later so that only specific lines will get edited)

My code:

#!/usr/bin/python3.4

file = open('testfile', 'r+')

readlinebyline = file.readline()

for i in range(0, len(readlinebyline)):
 readlinebyline.write(' ' + 'checked')

print('done')

I want my testfile to look like this afterwards:

line1 checked
line2 checked
line3 checked
...

But instead it looks like this:

line1
line2
line3
 checked checked checked

How do I get the program to stop after each line and then add something new to it?

Upvotes: 1

Views: 504

Answers (4)

lpozo
lpozo

Reputation: 598

with open('file.txt', 'r') as f:
    content = f.readlines()

with open('file.txt', 'w') as f:
    for line in content:
        f.write(line.strip('\n') + ' checked\n')

Upvotes: 0

Divya
Divya

Reputation: 13

testfile=open('uat_config.conf', 'r+')
readlinebyline=testfile.readlines()
for i in range(0, len(readlinebyline)):
 testfile.write("CHECKED "+ str(readlinebyline[i]))
print('done')

Upvotes: 0

be_good_do_good
be_good_do_good

Reputation: 4441

You can make use of readlines

with open('testfile', 'r') as file:
    # read a list of lines into data
    lines = file.readlines()

with open('testfile', 'w') as file:
    for line in lines:
        # do your checks on the line..
        file.write(line.strip() + ' checked' )

print('done')

Upvotes: 1

Cole
Cole

Reputation: 1755

I'd recommend going line by line writing the file to a new file and then moving that new file to the original file which will overwrite it:

import shutil

filename = '2017-11-02.txt'
temp_filename = 'new.txt'

with open(filename, 'r') as old, open(temp_filename, 'w') as new:
    # Go line by line in the old file
    for line in old:
        # Write to the new file
        new.write('%s %s\n' % (line.strip(),'checked'))

shutil.move(temp_filename, filename)

Somewhat related answer that I based this off of: https://stackoverflow.com/a/16604958/5971137

Upvotes: 0

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