Getting next line in a file

Question

I am reading in a file and wonder if there's a way to read the next line in a for loop?

I am currently reading the file like this:

file = open(input,"r").read()
for line in file.splitlines():
  line = doSomething()

So is there anyway I can retrieve the next line of the file in that for loop such that I can perform some operation in the doSomething() function?

Answer 1

Just loop over the open file:

infile = open(input,"r")
for line in infile:
    line = doSomething(line, next(infile))

Because you now use the file as an iterator, you can call the next() function on the infile variable at any time to retrieve an extra line.

Two extra tips:

1. Don't call your variable file; it masks the built-in file type object in python. I named it infile instead.

2. You can use the open file as a context manager with the with statement. It'll close the file for you automatically when done:

   with open(input,"r") as infile:
       for line in infile:
           line = doSomething(line, next(infile))