for loop not iterating over file

Question

To my eyes the second for loop should be entered but it never does. Why is this? It's like the file is empty but I can assure you it's not.

def remove_none():

# remove contents of temp.txt
file = open('temp.txt', 'w')
file.truncate()
file.close()    

with open("temp.txt", "a") as temp:
    with open("temp_copy.txt") as temp_copy:

        num_of_lines = 0
        other_IPs = 0

        # count the number of lines in temp_copy.txt
        for _ in temp_copy:
            num_of_lines += 1
        other_IPs = num_of_lines-3
        print "\nThere are {} IP's excluding router and you.\n".format(other_IPs)

        count = 0
        os.system("cat temp_copy.txt")

        **# this is the second for loop**
        for line in temp_copy:
            count =+ 1
            print count
            if count == 1:
                # run this on the first line
                temp.write(line)

            elif count == num_of_lines:
                # run this on the last line 
                # remove the last line
                pass
            else:
                # run this on every other line
                line = line[4:]+"\n"
                temp.write(line)

oh and iv'e added print statements just before and after the second for loop so I know that it's not entering. It just passes the loop and continues with the program. It also gives no errors. — Aaron, Aug 19 '17 at 23:03
Possible duplicate of: [https://stackoverflow.com/questions/10255273/iterating-on-a-file-using-python](https://stackoverflow.com/questions/10255273/iterating-on-a-file-using-python) — vielkind, Aug 19 '17 at 23:05

score 0 · Answer 1 · edited Aug 21 '17 at 01:15

0

The problem is

count =+1

it should be

count +=1

REMEMBER THIS:

+= IS THE ADDITION OPERATOR =+ MEANS THE VARIABLE IS EQUAL TO THE POSITIVE NUMBER SO count =+ 1 means count is equal to positive 1 while count +=1 means count plus 1

That should solve the problem!

Also, the first loop reads the whole file and you need to tell it to start from the beginning again.

edited Aug 21 '17 at 01:15

Pang

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answered Aug 19 '17 at 23:18

Victor Li

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Good spot, but it was not the problem. Thanks though. – Aaron Aug 19 '17 at 23:52

D.Shawley · Answer 2 · 2017-08-20T00:13:20.923

0

The second loop doesn't run because the first loop reads the entire file. In other words, the file iterable is at the end of the sequence when the first loop completes. If you want to iterate over the file twice you can reset the location with file.seek(0).

edited Aug 20 '17 at 00:13

answered Aug 19 '17 at 23:34

D.Shawley

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Thanks you very much, you hit the nail on the head. The problem is fixed. – Aaron Aug 19 '17 at 23:50

for loop not iterating over file

2 Answers2