Question

if I have a text file like this:

[001]This is line 1.
[002][too long]This is line 2 but it's Tooooo
oooo long!
[003]This is line 3.

I write a ‘for line in fileA’ to read this file like:

for line in fileA:
    ...

now I need to merge the current line and the next line when line.find(“[too long]”)>=0.
How should I do?

PS:
I wrote:

for line in fileA:
    if line.find("[too long]")>=0:
        loc = fileA.tell()
        fileB = open("file.txt") #open this file again
        fileB.seek(loc)
        line += fileB.readline().strip()

but it did not work. why?

Answer 1

Sounds too much overhead with extra reading of the file. Try this:

with open('file.txt') as f:
    for line in f:
        if '[too long]' in line:
            line = line.rstrip('\r\n') + next(f)
        print line

prints

[001]This is line 1.

[002][too long]This is line 2 but it's Tooooooooo long!

[003]This is line 3.

This appends the following line if [too long] is found in a line. Maybe you want to append all further lines until a line starts with something like [xxx]?