hash

问题 I know the difference between Hashtable and HashMap. However, both these classes seemingly are using a hash function to get the job done. Is there a difference between the hash function used in Hashtable, and the hash function used in HashMap? In particular, is there a difference between the hashing algorithm they use? What is the formula used to hash in these two classes? In other words, is the way for calculating index (hash value) different? 回答1: In particular, is there a difference

问题 Is there a way to get a sub-hash? Do I need to use a hash slice? For example: %hash = ( a => 1, b => 2, c => 3 ); I want only %hash = ( a => 1, b => 2 ); 回答1: Hash slices return the values associated with a list of keys. To get a hash slice you change the sigil to @ and provide a list of keys (in this case "a" and "b" ): my @items = @hash{"a", "b"}; Often you can use a quote word operator to produce the list: my @items = @hash{qw/a b/}; You can also assign to a hash slice, so if you want a

问题 I have designed a signup page in C# and all users have to enter their password then the program will hash the password before saving it on a database with a SHA512 hashing method. Now, I want to verify entered password on the login page with the saved password on database. Below code is the method that I used to hash the passwords. Now how can I verify entered password on login page??? byte[] infos = System.Text.Encoding.ASCII.GetBytes(txtPassword.Text); infos = new System.Security

问题 Say a I have a dataclass in python3. I want to be able to hash and order these objects. I only want them ordered/hashed on id. I see in the docs that I can just implement __hash__ and all that but I'd like to get datacalsses to do the work for me because they are intended to handle this. from dataclasses import dataclass, field @dataclass(eq=True, order=True) class Category: id: str = field(compare=True) name: str = field(default="set this in post_init", compare=False) a = sorted(list(set([

问题 I am learning Flask through Miguel Grinberg's awesome tutorial. In that chapter, He suggests storing user's password hash rather than the password itself for security reasons. The functions been used are generate_password_hash , check_password_hash . But even if you call generate_password_hash with the same string, you can get different hash values : Then how does the check_password_hash work if the same string can have as many hash values as it like? 回答1: Passwords are hashed with a salt,

问题 In Perl 5, if I want to see the contents of a hash, I can use Data::Show, Data::Dump, or Data::Dumper. For example: use Data::Show; my %title_for = ( 'Book 1' => { 'Chapter 1' => 'Introduction', 'Chapter 2' => 'Conclusion', }, 'Book 2' => { 'Chapter 1' => 'Intro', 'Chapter 2' => 'Interesting stuff', 'Chapter 3' => 'Final words', } ); show(%title_for); Which outputs: ======( %title_for )======================[ 'temp.pl', line 15 ]====== { "Book 1" => { "Chapter 1" => "Introduction", "Chapter 2

问题 In the browser, I read in a file using the JS FileReader().readAsBinaryString(). Using the CryptoJS library I can MD5 hash the data. This works fine but I do not know how to handle large files. E.g. Just reading a 2GiB file crashes the browser window. I can slice blobs from the file data and hash that as I go but wouldn't this prevent anyone else from verifying the same hash without following the same steps as me? Is there a way to get the md5 hash of a large file in this circumstance? How

问题 I have a need to verify password hashes generated using python passlib. My objective is to use passlib's pbkdf2_sha512 scheme for hashing all user passwords. However, due to the nature of our backend, I need to verify this password from php scripts, js and java. I haven't found libraries in either of them that can take a passlib hash and verify the password. I was wondering if there exist one before I set out to implement passlib's hashing algorithm in php, js and java. 回答1: I can offer this

问题 I'm currently doing this (see snippet below) to get an md5 hash string for the image files I'm uploading (I'm using the hash as fileNames ): NOTE: I'm using the md5 package to generate the hash (it's loaded into the snippet). There are 4 available methods on FileReader() to read the files. They all seem to produce good results. readAsText(file) readAsBinaryString(file); readAsArrayBuffer(file); readAsDataURL(file); Which is should I be using in this case and why? Can you also explain the

问题 After checking this Ruby convert array to nested hash and other sites I am not able to achieve the following convertion: I have this: {"a"=>"text"} {"b"=>{"x"=>"hola"}} {"b"=>{"y"=>"pto"} } and I want to obtain: {"a"=>text, b=>{"x" => "hola", "y" => "pto" } } Until now the code seems like this: tm =[[["a"],"text"],[["b","x"],"hola"],[["b","y"],"pto"]] q = {} tm.each do |l| q = l[0].reverse.inject(l[1]) { |p, n| { n => p } } i += 1 end I tried with merge , but it overwrites the keys!. I tried