View source for Software:Diff-Text

{{Infobox software
| name                   = Diff Text
| logo                   = DiffEngineX_Icon.png
| logo size              = 32px
| developer              = DiffEngineX LLC
| released               = Oct 29, 2012
| programming language   = [[C Sharp (programming language)|C-sharp]]
| operating system       = Any
| genre                  = Data comparison
| license                = Closed Source
| website                = [http://www.diff-text.com diff-text.com]
}}

[[File:Diff-Text.com Screenshot Showing Detection Of Moved And Reordered Text.png|thumbnail|Moved text is colored blue or gray. Re-ordered text has its background color changed to alternately light blue and yellow.]]

'''Diff-Text''' is a [[Web application|web-based]] software tool that identifies differences between two blocks of plain text. It operates on a closed-source model and offers a donation or pay-what-you-want payment option.<ref>HVG Weekly [http://hvg.hu/Tudomany/20121102_Igy_hasonlithat_ossze_ket_szoveget_a_lege], 2 November 2012. Retrieved on 8 December 2012.</ref><ref>{{Cite web |title=diffenginex / Diff Text / wiki / Home — Bitbucket |url=https://bitbucket.org/diffenginex/diff-text/wiki/Home |access-date=2023-04-28 |website=bitbucket.org}}</ref> To be compared, text is pasted directly into the web-page. Diff-Text was developed by [[Software:DiffEngineX|DiffEngineX]] LLC and uses improved [[Algorithm|algorithms]] originally developed for the spreadsheet compare tool DiffEngineX. It allows the user to choose between comparing on the level of paragraphs, whole lines, words, or characters. If comparing whole lines, only the line that is not a part of the other block will be reported. Diff Text considers a paragraph to be any line ending with a [[Software:Microsoft Windows|Windows]], [[Software:Macintosh operating systems|Macintosh]] or [[Software:Unix|Unix]] line terminator.

The website can combine the original and modified text blocks into one pane with all differences highlighted. Alternatively, the marked-up original and modified text blocks can be displayed in individual panes. Navigation from one difference to the next is supported.

All of the above features are not unique and can be found in other text comparison tools. The software can display just the differences, the differences with a variable amount of context on either side or the whole marked-up text. The website supports the use of [[Transport Layer Security|SSL]] ("https") so confidential text can be compared. The algorithm used by Diff-Text is used by Selection Diff Tool, which is an app for [[Software:Microsoft Word|Microsoft Word]] and [[Software:Microsoft Excel|Excel 2013]].<ref>Office.Microsoft.com [https://store.office.com/selection-diff-tool-WA103863850.aspx?assetid=WA103863850], 26 November 2012. Retrieved on 8 December 2012.</ref>{{better source|date=September 2016}}

==Limitations of using the longest common subsequence algorithm==
Diff-Text has the ability to spot text that has either been moved up or down in the document and placed into a new context. To avoid spurious similarities being flagged, the software allows the user to specify the minimum number of adjacent words or characters to be reported as a move. Text movements are reported such that the number of individual edits to transform the original text into the modified text are at a minimum.

The vast majority of text comparison software based on the [[Longest common subsequence problem|longest common subsequence problem]] algorithm incorrectly report moved text as unlinked additions and deletions. The algorithm only reports the longest in-order run of text between two documents. Text moved out of the longest run of similarities is missed.

Heuristics are not used. Any similarity between the two documents above the specified minimum will be reported (if detecting moves is selected). This is the main difference between Diff-Text and most other text comparison algorithms. Diff-Text will always match up significant similarities even if contained within non-identical or moved lines. It never resorts to guessing or the first match that happens to be found, which may result in non-optimal matches elsewhere.

Diff-Text can spot sentence re-ordering within a paragraph. To indicate this, the background color of the text changes to light blue and yellow.

If the user specifies text movements should not be detected, its algorithm runs in (m log n) time, which is an improvement from the standard quadratic time often seen in software of this type. m and n refer to the sizes of the original and modified texts.

== References ==
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== External links ==
* [http://www.diff-text.com/ Official website]
* [http://download.cnet.com/Diff-Text/3000-2351_4-75805636.html On Download.com]


[[Category:Data differencing]]

{{Sourceattribution|Diff-Text|1}}