Compare two files, find the difference?

Question

I have two files with the following structure.

File A:

asd fds sdf asdf

File B:

asd sdf

I want to find the difference between these two files.

This time the result should be fds, asdf.

How can I do it with c++ or linux?

Load file content into std::set<std::string>, then setA - setB? — billz
– billz, Commented Jul 8, 2013 at 0:59

Aman Deep Gautam · Accepted Answer · 2013-07-08 00:57:56Z

2

diff A B returns

2d1 < fds 4d2 < asdf

answered Jul 8, 2013 at 0:57

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1 Comment

I personally prefer the output of diff -u, but yes, diff is a very useful program that all *nix users should be aware of.

jww · Accepted Answer · 2014-05-01 03:15:44Z

This answer was posted by @sflee in his question. It was moved into this answer block.

Solution:

Here is the way I used finally, just in case that I forget this in the future. I got A.txt and B.txt:

sort A.txt | uniq > A2.txt sort B.txt | uniq > B2.txt diff A2.txt B2.txt | grep '<' > data_B2_is_missing.txt