Question

I’m using + sign to add up 2 MD5 hashes like so:

md5('string1') + md5('string2')

now if I did this with strings, like so:

'string1' + 'string2'

…PHPp would give me 0 as a return value. However, with MD5 hashes, it always returns a numeric value, for which I cannot determine any origin.

Answer 1

It will depend on the hash values generated by your strings. When adding “string” values, PHP’s behaviour (and it is well documented) is to take any leading numeric characters and treat them as an integer… if there are no leading numerics, then it will be treated as 0.

So

"1st String" + "2nd String" => 1 + 2 => 3

With your data

md5('string1') = '34b577be20fbc15477aadb9a08101ff9'
md5('string2') = '91c0c59c8f6fc9aa2dc99a89f2fd0ab5'

giving

34 + 91 => 125

Now why are you trying to add hash values?