How to calculate similarity (in percentage) between strings in PHP?

Question

I would like to know how to calculate the similarity, in percentage, between two strings with PHP?

For example:

• I got you a present!
• I want some presents from you!

Answer 1

The best native form of PHP itself is this:

$var_1 = 'Eu tenho um presente pra vocês!'; 
$var_2 = 'Eu quero alguns presentes de vocês!'; 

similar_text($var_1, $var_2, $percentual); 

echo $percentual; 
// 73.529411764706 

Demo: http://sandbox.onlinephpfunctions.com/code/2ac97ccb9a14cf093f4c7fe6580ed626dda1e855