Subtract two strings in PHP or mySQL to count differences [duplicate]

Question

Is it possible to return the number of characters which differ between two strings?

In my case, I would like to run a check to quantify how much a user's draft has changed vs the database version. With this information, the system can decide weather or not the draft needs to be auto-saved.

For example:

echo string_diff("Hello world", "Hi World");

This should output "5", indicating that characters "ello" & "W" are different.

Is this possible with PHP? How about with mySQL?

or as simple as php.net/manual/en/function.strcmp.php or substr_compare and co... — Twisted1919
– Twisted1919, Commented May 27, 2013 at 19:28

Orangepill · Accepted Answer · 2013-05-27 19:35:27Z

3

On the PHP side your options are

similar_text which calculates the percent similarity between two strings
levenshtein - which calculates the edit distance between two strings (the number of key strokes it takes to transform string a into string b)

on mysql you can use this user defined function to calculate the levenshtein distance

answered May 27, 2013 at 19:35

Orangepill

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