Print one line at a time from text file using python

Question

ok so I've poured over this site and I CAN'T find anything that works. here is my code

print("Type the filename")
file_again = raw_input("> ")

lines = [6]
with open(file_again, 'r') as f:
    lines = f.read().splitlines()
for line in lines:
    print line 

BUT I can't get it to print out line by line and all it would be is one digit in each line. I'd also like to use a counter but I can't get that syntax right. i tried enumerating but that didnt work out well for me

Answer 1

print("Type the filename")
file_again = raw_input("> ")

with open(file_again, 'r') as f:
    lines = f.readlines()

for num, line in enumerate(lines, 1):
    print "%s: %s" % (num, line) 

Basically, you had two issues:

1. You need to loop over the lines. For this, use readlines() , which returns all the lines in a list you can iterate through.
2. You need to print a counter and the line value. For this, enumerate() will provide you a counter in the for loop concisely. Then, format the printed line to show both the counter and the line value.

Answer 2

File objects in Python are iterators. So you can iterate over them directly:

from __future__  import print_function # get Python 3 printing in Python 2

with open(file_again) as fobj:
    for lineno, line in enumerate(fobj, 1):
          print('{}: {}'.format(lineno, line), end='')

The end='' does not add a newline to the print because each line has a newline at its end already.

The advantage of this approach is that you can easily work with large files because you don't need to read the whole file at once.