file compareson

[eileen1017]

I have two files A and B. The content of file A is as follows:
aaa
bbb
ccc
111
222
333

The content of file B is as follows:
111
222
333
ddd
444
eee

There are three lines in file B match those of file A. I need to write a scipt that compares those two files. If there is a match line, then I need to remove those line from file B. How would I be able to do that? Please help. Thanks.

 

[KevinADC]

is this homework? Was your other question also homework?

 

[eileen1017]

No, this is not home work. I use this file name and content just for example purpose. The real file I can not show since it is confidential. I am new to the job.

 

[fdf]

for i in `cat filea`
do
grep -v $i fileb > filec
mv filec fileb
done

 

[KevinADC]

fdf,

this is the perl forum.

 

[stevexff]

Also, for anything over a few hundred lines per file, this is going to be hugely inefficient, as file b has to be read and compared once for every line in file a.

Eileen - what do you expect to happen if there are duplicate lines in file b? Does the order of the contents of fileb need to be preserved?

#!/usr/bin/perl
use strict;
use warnings;
my %filea;

open(FILEA, "filea.txt") or die $!;

while (<FILEA>) {
    $filea{$_}++;
}

open(FILEB, "fileb.txt") or die $!;

while (<FILEB>) {
    print $_ unless exists $filea{$_};
}

At the moment this print the results. You can either redirect the output to a file, or change it to write to a file yourself.

Steve

[small]"Every program can be reduced by one instruction, and every program has at least one bug. Therefore, any program can be reduced to one instruction which doesn't work." (Object:erlDesignPatterns)[/small]