hash

问题 I have just picked up Perl. I have a little confusion with accessing hash values. Below is the code where I am trying to access the values of a hash inside a hash. Since am using a simple text editor to code, I am not able to figure out what can be the problem. Please help my %box = ( Milk => { A => 5, B => 10, C => 20, }, Chocolate => { AB => 10, BC => 25, CD => 40, }, ); foreach my $box_key(keys %box) { foreach my $inside_key (keys %box{box_key}) print "$box_key"."_$inside_key""is for

问题 Is there a way to create a hash of hashes in C++? Effectively I am trying to do what you can do in Perl but only in C++. Here is an example of Perl code I would like to have happen in C++ %hash = ( gameobject1 => { position => { x_loc => 43, y_loc => 59, } rect_size => { width => 5, height => 3, } collidable => 1, sounds => { attack => "player_attack.ogg", jump => "player_jump1.ogg", jump_random => [qw/player_jump1.ogg player_jump2.ogg player_jump3.ogg/] } }, gameobject2 => { position => { x

问题 I want to create a MD5 hash code in Qt. My code : QString queryStr; queryStr = QString("%1") .arg(QString(QCryptographicHash::hash(ui->txtPassword->text(),QCryptographicHash::Md5).toHex())); but my code does not work! hash method does not work in Qt ! Any suggestion? 回答1: text() returns QString , QCryptographicHash::hash requires QByteArray and there is no implicit conversion, so you should do this by yourself. Use something like this: QString queryStr; ui->lineEdit_2->setText("hash");

问题 Using the HTML5 File API and any JavaScript crypto library, how can I generate an MD5 hash of the file? To read the file: var reader = new FileReader(); reader.onload = function(e) { var contents = e.target.result; // What goes here? }; reader.readAsBinaryString(data.files[0]); 回答1: This goes there: var reader = new FileReader(); reader.onload = function(e) { var contents = e.target.result; // This goes here: var hash = CryptoJS.MD5(CryptoJS.enc.Latin1.parse(contents)); }; Be sure you include

问题 I know that Java has beautiful inbuilt support for the HashMaps or HashTables. Does anybody have knowledge that what kind of hashing functions or techniques are employed by Java language? Is it possible to tweak those functions to be able to make them more specific to one's application in order to improve performance and reducing access time? Thanks a lot for reading! 回答1: Java allows you to override the hashCode() method for your Classes to use a hashing algorithm that is not only well

问题 I have the following method: def test(first_param = nil, keyword_arg: nil) puts "first_param: #{first_param}" puts "keyword_arg: #{keyword_arg}" end All the following calls do what I expect them to do: test(:something) #=> first_param: something # keyword_arg: test(nil, keyword_arg: :keyword_arg) #=> first_param: # keyword_arg: keyword_arg test({ first_param: :is_a_hash }, keyword_arg: :is_still_working) #=> first_param: {:first_param=>:is_a_hash} # keyword_arg: is_still_working But omitting

问题 Does a string hash exist which can ignore the order of chars in this string? Eg."helloword" and "wordhello" can map into the same bucket. 回答1: If you don't mind strings like "ac" and "bb" generating the same hash value, you can add the values of the characters together. (a + b + c is equal to a + c + b.) If you want to reduce the possibility of hash code collisions of that kind, then you can multiply the values of the characters together. (a * b * c is also equal to a * c * b.) If that's not

问题 Since MySQL uses BTREE by default when creating an index, is there some instance when I can use HASH ? For example, if my table only consists of Foreign Keys which are just INT UNSIGNED values. Is it a good improvement to override BTREE with HASH in this case? Not sure if it matters, but I'm using InnoDB . 回答1: The HASH index type is only supported for MEMORY (aka HEAP ) storage engine. 来源： https://stackoverflow.com/questions/14418260/mysql-when-can-i-use-hash-instead-of-btree

问题 Since MySQL uses BTREE by default when creating an index, is there some instance when I can use HASH ? For example, if my table only consists of Foreign Keys which are just INT UNSIGNED values. Is it a good improvement to override BTREE with HASH in this case? Not sure if it matters, but I'm using InnoDB . 回答1: The HASH index type is only supported for MEMORY (aka HEAP ) storage engine. 来源： https://stackoverflow.com/questions/14418260/mysql-when-can-i-use-hash-instead-of-btree

问题 I am developing a web application in which I need to encrypt sensitive information. My plan is to use use AES-256 where the private key is encrypted by a hash of the user's password. I need to store the hash of the password for authentication purposes, but it obviously can't be same used to encrypt the private key. My current thought is to use bcrypt to generate a key to be used to encrypt the private key. For authentication, my thought was to simply hash the password using bcrypt and then