similar_text
(PHP 4, PHP 5, PHP 7, PHP 8)
Calculate the similarity between two strings
Description
This calculates the similarity between two strings as described in Classics. Note that this implementation does not use a stack as in Oliver's pseudo code, but recursive calls which may or may not speed up the whole process. Note also that the complexity of this algorithm is O(N**3) where N is the length of the longest string.
Parameters
string1The first string.
string2The second string.
NoteSwapping the
string1andstring2may yield a different result; see the example below.percentBy passing a reference as third argument,
similar_text()will calculate the similarity in percent, by dividing the result ofsimilar_text()by the average of the lengths of the given strings times100.
Return Values
Returns the number of matching chars in both strings.
The number of matching characters is calculated by finding the longest first common substring, and then doing this for the prefixes and the suffixes, recursively. The lengths of all found common substrings are added.
Examples
similar_text() argument swapping example
This example shows that swapping the string1 and string2 argument may yield different results.
<?php
$sim = similar_text('bafoobar', 'barfoo', $perc);
echo "similarity: $sim ($perc %)\n";
$sim = similar_text('barfoo', 'bafoobar', $perc);
echo "similarity: $sim ($perc %)\n";The above example will output something similar to:
similarity: 5 (71.428571428571 %)
similarity: 3 (42.857142857143 %)