Looking for a method to tell the difference between two lines

Question

I was wondering if there are any free string comparison implementations, which suggests the difference between the two multi-line strings. I'm looking for something like a Microsoft SourceSafe comparison screen.

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

(A use case would be to compare static html pages to see if there are any changes, such as ads or new downloads. My university has separate pages for each course I attend.)

Answer 1

It is looking for a diff library, not a diff tool.

A quick google search calls several:

• Google diff match patch
• Diff algorithm
• Buggy is an old diff that is not supported (great link I know)

Answer 2

Are you looking for a free diff tool like Diffuse ?

EDIT: Initially, I had a note saying that this was not related to programming, but I realized that I was mistaken when I reread your question. I think you want to pull out the html and make diff in the tool you are writing. If this is what you are trying to do, as opposed to manual comparisons, then Diffuse will not help you, although the project is open source. This may give you some results.

Answer 3

If you just want to find out if there are differences: use the hash algorithm (crc, md5, sha) and check if the value has changed.

What you describe is more like a diff tool (a good search word for this), which visually shows you the differences in the source files, but I doubt what you need if for a given usecase. See above.

Or check if your university really supports caching, and just look at the Http HEAD answer for the site you are interested in.

Answer 4

You might want to check Does anyone have a diff algorithm for the displayed HTML?