In Ruby 2.3(.0), these are all the same: {:”a” => 1} {“a”: 1}, {:a => 1} {a: 1} They all translate to the same thing: a is a symbol in all these cases. {“a”=>1} is different: a is a string in this case.
RSpec allows you to use the have_key predicate matcher to validate the presence of a key via has_key?, like so: subject { described_class.order_items_by_revenue } it “includes revenue key” do expect(subject.first).to have_key(:revenue) end
There are three concepts to grasp when trying to understand id, hash and the == and is operators: identity, value and hash value. Not all objects have all three. All objects have an identity, though even this can be a little slippery in some cases. The id function returns a number corresponding to an object’s … Read more
PBKDF2 You were really close actually. The link you have given shows you how you can call the Rfc2898DeriveBytes function to get PBKDF2 hash results. However, you were thrown off by the fact that the example was using the derived key for encryption purposes (the original motivation for PBKDF1 and 2 was to create “key” … Read more
So I finally figured it out. The “infohash” is the SHA1 Hash over the part of a torrent file that includes: ITEM: length(size) and path (path with filename) Name: The name to search for Piece length: The length(size) of a single piece Pieces: SHA1 Hash of EVERY piece of this torrent Private: flag for restricted … Read more
a_hash = {‘a’ => 30, ‘b’ => 14} b_hash = {‘a’ => 4, ‘b’ => 23, ‘c’ => 7} a_hash.merge(b_hash){ |k, a_value, b_value| a_value + b_value } => {“a”=>34, “b”=>37, “c”=>7} b_hash.merge(a_hash){ |k, b_value, a_value| a_value + b_value } => {“a”=>34, “b”=>37, “c”=>7}
You can do it like this (in a working snippet): var input = { “fruit” : [“mango”,”orange”], “veg” : [“carrot”] } var output = [], item; for (var type in input) { item = {}; item.type = type; item.name = input[type]; output.push(item); } // display result document.write(JSON.stringify(output)); Or, if you or someone else has been … Read more
Example: def foo(regular, hash={}) puts “regular: #{regular}” puts “hash: #{hash}” puts “a: #{hash[:a]}” puts “b: #{hash[:b]}” end foo(“regular argument”, a: 12, :b => 13) I use hash={} to specify that the last argument is a hash, with default value of empty hash. Now, when I write: foo(“regular argument”, a: 12, :b => 13) It’s actually … Read more
I have this in a category on NSString (available at https://github.com/hypercrypt/NSString-Hashes): #import <CommonCrypto/CommonDigest.h> … – (NSString *)sha1 { NSData *data = [self dataUsingEncoding:NSUTF8StringEncoding]; uint8_t digest[CC_SHA1_DIGEST_LENGTH]; CC_SHA1(data.bytes, (CC_LONG)data.length, digest); NSMutableString *output = [NSMutableString stringWithCapacity:CC_SHA1_DIGEST_LENGTH * 2]; for (int i = 0; i < CC_SHA1_DIGEST_LENGTH; i++) { [output appendFormat:@”%02x”, digest[i]]; } return output; } Starting with Xcode … Read more
Basically it’s because the output of MD5 contains less information than the input. This is basically what distinguishes a hash algorithm from an encryption algorithm. Here’s a simple example: imagine an algorithm to compute the hash of a 10-digit number. The algorithm is “return the last 2 digits.” If I take the hash of 8023798734, … Read more