hashcode

How to Implement T-SQL CHECKSUM() in JavaScript for BigQuery?

由 六眼飞鱼酱① 提交于 2019-12-12 06:39:11
问题 The end result I'm looking for is to implement T-SQL CHECKSUM in BigQuery with a JavaScript UDF. I would settle for having the C/C++ source code to translate but if someone has already done this work then I'd love to use it. Alternatively, if someone can think of a way to create an equivalent hash code between strings stored in Microsoft SQL Server compared to those in BigQuery then that would help me too. UPDATE: I've found some source code through HABO's link in the comments which is

Implementing a Number System in Java: Mutable vs. Immutable

由 时光总嘲笑我的痴心妄想 提交于 2019-12-12 04:38:29
问题 I am implementing classes for rational numbers, but the problems and issues are essentially the same for complex numbers as well as other classes intended to be used in applications with a significant number of calculations performed on a given mathematical object. In the libraries distributed with the JRE and in many third-party libraries, number classes are immutable. This has the advantage that "equals" and "hashcode" can be reliably implemented together as intended. This will enable

Is It Possible to Use Hashcodes as a Bitmask to Efficiently Store/Track Collection Membership?

由 冷暖自知 提交于 2019-12-12 03:48:48
问题 Currently I have a solution where I keep track of objects I am interested in by getting their hashcode via Object.GetHashCode and then storing them in a HashSet<int> . However, I have also been learning about bitmasks and bitwise operations and I am quite intrigued by them. Here is a great question that I found close to what I am looking to do. However, I cannot seem to make this work efficiently for hash codes. There is also this question, but it seems to deal with 5-bit numbers, when hash

Generating hashCode() for a custom class

由 丶灬走出姿态 提交于 2019-12-12 03:26:23
问题 I have a class named Dish and I handle it inside ArrayList s So I had to override default hashCode() method. @Override public int hashCode() { int hash =7; hash = 3*hash + this.getId(); hash = 3*hash + this.getQuantity(); return hash; } When I get two dishes with id=4 , quan=3 and id=5 , quan=0 , hashCode() for both is same; ((7*3)+4)*3+3 = 78 ((7*3)+5)*3+0 = 78 What am I doing wrong? Or the magic numbers 7 and 3 I have chosen is wrong? How do I properly override hashCode() so that it

Segmentation fault 11, python hash with lists, hashing 1 million objects

由 北城以北 提交于 2019-12-12 03:05:08
问题 When I try to make and hash objects from a file, containing one million songs, I get a weird segmentation error after about 12000 succesfull hashes. Anyone have any idea why this: Segmentation fault: 11 happens when I run the program? I have these classes for hashing the objects: class Node(): def __init__(self, key, value = None): self.key = key self.value = value def __str__(self): return str(self.key) + " : " + str(self.value) class Hashtable(): def __init__(self, hashsize, hashlist =

password_verify always invalid password although password is correct

由 南楼画角 提交于 2019-12-12 02:33:36
问题 I don't have idea what is the trouble in my code hash.php(insert bycryp password) **<?php $con = new mysqli("localhost", "root", "", "hast") or die(mysqli_error()); if (array_key_exists("f5", $_GET)) { $w5 = $_GET['f5'];//pass } if (array_key_exists("f6", $_GET)) { $w6 = $_GET['f6'];//pass } $salt = md5(uniqid(rand())); $options = [ 'cost' =>11, 'salt' => $salt ]; $hash_password = password_hash($w6, PASSWORD_BCRYPT, $options)."\n"; $sql = mysqli_query($con, "INSERT INTO `pass`(`nama`, `hash

hashCode() method using HashMap

由 假如想象 提交于 2019-12-12 01:43:59
问题 Do I have to override hashCode() method, if I'm going to customize HashMap ? UPD: For example: import java.util.HashMap; import java.util.Objects; /** * * @author dolgopolov.a */ public class SaltEntry { private long time; private String salt; /** * @return the time */ public long getTime() { return time; } /** * @param time the time to set */ public void setTime(long time) { this.time = time; } /** * @return the salt */ public String getSalt() { return salt; } /** * @param salt the salt to

Java collections - overriding equals and hashCode

由 房东的猫 提交于 2019-12-12 00:33:30
问题 class Hash { int a; Hash(int h){ a=h; } public boolean equals(Object o) { Boolean h=super.equals(o); System.out.println("Inside equals "); return h; } public int hashCode() { System.out.println("Inside Hash"); return 2; } } public class Eq { public static void main(String...r) { HashMap<Hash,Integer> map=new HashMap<Hash,Integer>(); Hash j=new Hash(2); map.put(j,1); map.put(j,2); System.out.println(map.size()); } } output was inside hash inside hash 1 Since it returns the same hashcode , the

Hash code for expandable class (future proof)

由 陌路散爱 提交于 2019-12-11 20:51:47
问题 Since I don't have any great skills in math, I ask you if there exists any algorithm that I should use for a class which probably will change in the future. Consider following scenario: Class "Roles" has following fields: private boolean admin; private boolean printer; After some weeks I decide to add a role "guest": private boolean admin; private boolean printer; private boolean guest; After some weeks I decide to remove the role "printer"; private boolean admin; private boolean guest; Since

JAVA中重写equals()方法为什么要重写hashcode()方法说明

由 我是研究僧i 提交于 2019-12-11 18:23:20
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 重写hashCode（）时最重要的原因就是：无论何时，对同一个对象调用hashCode()都应该生成同样的值。如果在将一个对象用put（）方法添 加进HashMap时产生一个hashCode()值，而用get()取出时却产生了另外一个 hashCode()值，那么就无法重新取得该对象了。所以，如果你的hashCode()方法依赖于对象中易变的数据，那用户就要小心了，因为此数据发 生变化时，hashCode()就会产生一个不同的hash码，相当于产生了一个不同的“键”。 Object的hashCode（）方法，返回的是当前对象的内存地址。下次如果我们需要取一个一样的“键”对应的键值对的时候，我们就无法得到一样的 hashCode值了。因为我们后来创建的“键”对象已经不是存入HashMap中的那个内存地址的对象了。 我们看一个简单的例子，就能更加清楚的理解上面的意思。假定我们写了一个类：Person （人），我们判断一个对象“人”是否指向同一个人，只要知道这个人的身份证号一直就可以了。 先来个没有重写Code类的hashcode()的例子吧，看看是什么效果： Java代码 package com.fit; import java.util.HashMap; /** * 身份证类 * * @author ZYD *
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