object

Return a reference by a class function and return a whole object in c++?

由 放肆的年华 提交于 2020-01-03 17:14:06
问题 Operator overloading in class CVector: CVector CVector::operator+ (CVector param) { CVector temp; temp.x = x + param.x; temp.y = y + param.y; return (temp); } and in main: CVector a (3,1); CVector b (1,2); CVector c; c = a + b; So an object is passed by value, and then another temp object is being created. I guess b is being passed by value, a is the one calling the + therefore the x and y belong to a and pram.x and param.y to b. temp is returned and the the copy assignment operator delivers

Java 8 函数式接口 - Functional Interface

由 梦想的初衷 提交于 2020-01-03 16:59:07
阅读目录 什么是函数式接口（Functional Interface） 函数式接口用途 关于@FunctionalInterface注解 函数式接口里允许定义默认方法 函数式接口里允许定义静态方法 函数式接口里允许定义java.lang.Object里的public方法 JDK中的函数式接口举例 参考资料 什么是函数式接口（Functional Interface） 其实之前在讲Lambda表达式的时候提到过，所谓的函数式接口，当然首先是一个接口，然后就是在这个接口里面 只能有一个抽象方法 。 这种类型的接口也称为SAM接口，即Single Abstract Method interfaces。 函数式接口用途 它们主要用在Lambda表达式和方法引用（实际上也可认为是Lambda表达式）上。 如定义了一个函数式接口如下： @FunctionalInterface interface GreetingService { void sayMessage(String message); } 那么就可以使用Lambda表达式来表示该接口的一个实现(注：JAVA 8 之前一般是用匿名类实现的)： GreetingService greetService1 = message -> System.out.println("Hello " + message); 关于

Class variables in React with ES6

由 ε祈祈猫儿з 提交于 2020-01-03 15:18:13
问题 This question might have been answered somewhere else, but before marking as duplicate, please help me with it. I am referring to the following codepen using react and d3: https://codepen.io/swizec/pen/oYNvpQ However, I am not able to figure out how can this codepen work with variables declared inside the class without any keywords: class Colors extends Component { colors = d3.schemeCategory20; width = d3.scaleBand() .domain(d3.range(20)); .... } When I try to execute this code, I get the

能快速理解Java_集合类_的文章

由 落花浮王杯 提交于 2020-01-03 15:14:05
这篇文章是我学习完Java集合类做的笔记和总结，也是用来记录自己从大一开始的IT生涯，如果你想认真细读这篇文章，请做好受虐的准备(建议电脑看)，因为这篇文章有点长，ヽ(ー_ー)ノ。 如果在看我这篇文章过程中，发现了错误，望指点。 一、什么是集合？ 举个例子：当你有很多书时，你会考虑买一个书柜，将你的书分门别类摆放进入。使用了书柜不仅仅使房间变得整洁，也便于以后使用书时方便查找。在计算机中管理对象亦是如此，当获得多个对象后，也需要一个容器将它们管理起来，这个容器就是集合。 集合本质是基于某种数据结构数据容器。常见的数据结构：数组（Array）、集（Set）、队列（Queue）、链表（Linkedlist）、树（Tree）、堆（Heap）、栈（Stack）和映射（Map）等结构。 下面便 一 . 一 介绍： 其中在两大接口中会有框架图，以方便大家学前、学后在大脑里可以形成一个思维导图，也方便大家检查自己对各各知识点的熟悉程度。 注意： 由于在集合中是有一个参数化类型的，所以在下面的代码里我会 指定成Object 。为什么我要指定为Object呢？因为Java中的Object类是所有类的超类。 先涉及一下泛型的定义：集合类 对象 = new 集合类 (); 也可以先前往 四、泛型，了解U•ェ•*U 二、Collection接口 1、集合类中Collection接口的介绍

empty() returning TRUE on object's non-empty property

由 前提是你 提交于 2020-01-03 14:56:16
问题 I've got a very weird and unexpected problem. empty() is returning TRUE on a non-empty property for a reason unknown to me. class MyObject { private $_property; public function __construct($property) { $this->_property = $property; } public function __get($name) { $priv_name = "_{$name}"; if (isset($this->$priv_name)) { return $this->$priv_name; } else { return NULL; } } } $obj = new MyObject('string value'); echo $obj->property; // Output 'string value' echo empty($obj->property); // Output

empty() returning TRUE on object's non-empty property

由 ￣綄美尐妖づ 提交于 2020-01-03 14:56:03
问题 I've got a very weird and unexpected problem. empty() is returning TRUE on a non-empty property for a reason unknown to me. class MyObject { private $_property; public function __construct($property) { $this->_property = $property; } public function __get($name) { $priv_name = "_{$name}"; if (isset($this->$priv_name)) { return $this->$priv_name; } else { return NULL; } } } $obj = new MyObject('string value'); echo $obj->property; // Output 'string value' echo empty($obj->property); // Output

why 2 objects of Integer class in Java cannot be equal

由 十年热恋 提交于 2020-01-03 11:00:09
问题 my code is: public class Box { public static void main(String[] args) { Integer z = new Integer(43); z++; Integer h = new Integer(44); System.out.println("z == h -> " + (h == z )); } } Output:- z == h -> false why the output is false when the values of both the objects is equal? Is there any other way in which we can make the objects equal? 回答1: You are trying to compare two different object and not their values. z and h points to two different Integer object which hold same value. z == h

When to create a class vs setting a boolean flag?

由 痴心易碎 提交于 2020-01-03 09:05:10
问题 I have an interesting question to pose; when should one create a model class/object as opposed to setting a boolean flag for data stored in a database? For example, say I have a Person class that has boolean flags for President, Guard, and PartTime. This class/model is treated differently depending on the value of the flags. So the President gets different privileges in the system from the Guard and from the PartTime(r). When would one use Single Table Inheritance to represent this

How to pass Objects between activities

由 ￡可爱￡侵袭症＋ 提交于 2020-01-03 06:39:35
问题 I have a feed object, that is filled with deserialized json data. I am trying to pass a feed object between 2 xamarin android activities. How can I accomplish this? I am aware of putseriazable but i'm not sure how to implement this. public class Feed { public class Author { public int id { get; set; } public string slug { get; set; } public string name { get; set; } public string first_name { get; set; } public string last_name { get; set; } public string nickname { get; set; } public string

accessing array and objects

由 社会主义新天地 提交于 2020-01-03 06:39:08
问题 I have a problem with printing my data. In my program, i get the data which was in object and put in an array. say array1[$id] = dataobject. the whole array1 then will be put to array2['list'] like array2['list'] = array1; the problem is how do i get the data such as the id, name and description.. here's the print_r of the whole array: this is actually the result of the array, i am not sure how to access this. i want to foreach and get the name and print them: Array ( [list] => Array ( [0] =>
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