Yes, there is a difference. These are legal: h = { :$in => array } h = { :’a.b’ => ‘c’ } h[:s] = 42 but these are not: h = { $in: array } h = { ‘a.b’: ‘c’ } # but this is okay in Ruby2.2+ h[s:] = 42 You can also use … Read more
To be able to use std::unordered_map (or one of the other unordered associative containers) with a user-defined key-type, you need to define two things: A hash function; this must be a class that overrides operator() and calculates the hash value given an object of the key-type. One particularly straight-forward way of doing this is to … Read more
How can I generate an MD5 hash in Java?
First, note that this behavior applies to any default value that is subsequently mutated (e.g. hashes and strings), not just arrays. It also applies similarly to the populated elements in Array.new(3) { [] }. TL;DR: Use Hash.new { |h, k| h[k] = [] } if you want the most idiomatic solution and don’t care why. … Read more
Well, you could look it up in Wikipedia… But since you want an explanation, I’ll do my best here: Hash Functions They provide a mapping between an arbitrary length input, and a (usually) fixed length (or smaller length) output. It can be anything from a simple crc32, to a full blown cryptographic hash function such … Read more
No. MD5 is not encryption (though it may be used as part of some encryption algorithms), it is a one way hash function. Much of the original data is actually “lost” as part of the transformation. Think about this: An MD5 is always 128 bits long. That means that there are 2128 possible MD5 hashes. … Read more
You should never escape, trim or use any other cleansing mechanism on passwords you’ll be hashing with PHP’s password_hash() for a number of reasons, the single largest of which is because doing additional cleansing to the password requires unnecessary additional code. You will argue (and you see it in every post where user data is … Read more
DISCLAIMER: This answer was written in 2008. Since then, PHP has given us password_hash and password_verify and, since their introduction, they are the recommended password hashing & checking method. The theory of the answer is still a good read though. TL;DR Don’ts Don’t limit what characters users can enter for passwords. Only idiots do this. … Read more