Algirdas Varnagiris » diff http://www.varnagiris.net The cyber-place where I live Thu, 18 Feb 2010 17:19:42 +0000 en hourly 1 http://wordpress.org/?v=3.0 How to compare text and mark differences using PHP http://www.varnagiris.net/2009/04/12/how-to-compare-text-and-mark-differences-using-php/ http://www.varnagiris.net/2009/04/12/how-to-compare-text-and-mark-differences-using-php/#comments Sun, 12 Apr 2009 08:09:27 +0000 Algirdas http://www.varnagiris.net/?p=117 I was looking for a simple class which will compare to strings and return a result with marked differences. What chars or words where removed and which were added. Just like wiki compare revisions. Actually i googled a lot and finally found a result:
The main class which do mostly all the job is Text_Diff, you can download it from http://pear.php.net/package/Text_Diff/

The other tool I used was http://software.zuavra.net/inline-diff/. It use Text_Diff and render results.
If you have two strings: “my blue pen” and “my red pen”, this is the diff and it will produce: “my <del>blue</del><ins>red</ins> pen”.
It does the following:

  • takes two strings
  • splits each of them into arrays containing one character per entry
  • considers the two arrays to be “lines” and uses Text_Diff from PEAR to compute a diff
  • it uses my own diff renderer which extends the one from Text_Diff and renders the differences “inline” using <del></del> and <ins></ins> to mark them. These tags are customizable.
  • finally, it returns the string consisting of the two originals mashed together, with the inline diffs applied.

Result example:
If you have two strings: “my blue pen” and “my red pen”, this is the diff and it will produce: “my bluered pen”.

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