Python: Writing to a File

Question

I've been having trouble with this for a while. How do I open a file in python and continue writing to it but not overwriting what I had written before?

For instance:

The code below will write 'output is OK'. Then the next few lines will overwrite it and it will just be 'DONE'

But I want both 'output is OK' 'DONE' in the file

f = open('out.log', 'w+')
f.write('output is ')
# some work
s = 'OK.'
f.write(s)
f.write('\n')
f.flush()
f.close()
# some other work
f = open('out.log', 'w+')
f.write('done\n')
f.flush()
f.close()

I want to be able to freely open and write to it in intervals. Close it. Then repeat the process over and over.

Thanks for any help :D

Answer 1

Open the file in append mode. It will be created if it does not exist and it will be opened at its end for further writing if it does exist:

with open('out.log', 'a') as f:
    f.write('output is ')
    # some work
    s = 'OK.'
    f.write(s)
    f.write('\n')

# some other work
with open('out.log', 'a') as f:
    f.write('done\n')