Looking for method to tell the difference between to strings

Question

Hello folks, I was wondering if there are any free implementations of a string compare, that tells the difference between two multiline strings. I'm lookin for something like the compare screen of Microsoft SourceSafe.

What I want to achieve is, is to compare two html websites and get an overview of the changes.

(The use case will be in comparing static html pages to find out if there are any changes, like annoucments or new downloads. My university hosts seperate pages for each course I visit.)

Answer 1

Are you looking for a free "diff" tool, like Diffuse?

EDIT: I initially had a note here suggesting this wasn't programming-related, but I realized I was wrong after re-reading your question. I think you want to pull the html and do the diff yourself in a tool that you're writing. If that is what you're trying to do, as opposed to a manual comparison, then Diffuse isn't going to help you, although the project is open-source. That may give you some leads.

Answer 2

If you just want to know if there are differences at all: Use a hashing algorithm (crc, md5, sha) and check if the value changed.

What you describe sounds more like a "diff" (good search word for that) tool that visually shows you the differences in the source files - but I doubt that you need if for the given usecase. See above.

Or check if your university actually supports caching in a decent way and just look at a Http HEAD response for the site you are interested in.

Answer 3

He's looking for a diff library, not a diff tool.

A quick search on google turns up a few:

• Google's Diff Match Patch
• Diff Algorithm
• Buggy old diff which isn't supported (great link I know)

Answer 4

You might want to check out Anyone have a diff algorithm for rendered HTML?