object

问题 Suppose I have an array of objects of type Foo in C++: Foo array[10]; In Java, I can set an object in this array to null simply by: array[0] = null //the first one How can I do this in C++? 回答1: Use pointers instead: Foo *array[10]; // Dynamically allocate the memory for the element in `array[0]` array[0] = new Foo(); array[1] = new Foo(); ... // Make sure you free the memory before setting // the array element to point to null delete array[1]; delete array[0]; // Set the pointer in `array[0]

问题 When calling Any() on a null object, it throws an ArgumentNullException in C#. If the object is null, there definitely aren't 'any', and it should probably return false. Why does C# behave this way? 回答1: When dealing with reference types, a null value is semantically different from an "empty" value. A null string is not the same as string.Empty , and a null IEnumerable<T> is not the same as Enumerable.Empty<T> (or any other "empty" enumerable of that type). If Any were not an extension method

问题 I want to access the instance created in t1 from outside the thread, is this possible? So I can close the socket after the thread is executed. Network class: public class Network { Socket socket; public void changeConnection(String command) throws Exception { // Whatever exceptions might be thrown if (command.equals("connect")) { socket = new Socket(server, port); } else if (command.equals("disconnect")) { socket.close(); } } } Main class: public class Project1 { public static void main

问题 I want to access the instance created in t1 from outside the thread, is this possible? So I can close the socket after the thread is executed. Network class: public class Network { Socket socket; public void changeConnection(String command) throws Exception { // Whatever exceptions might be thrown if (command.equals("connect")) { socket = new Socket(server, port); } else if (command.equals("disconnect")) { socket.close(); } } } Main class: public class Project1 { public static void main

问题 I have my DB in Excel and want to consult it to create reports in Word. I have searched and tried different options but none seem to work. Any suggestions would be of great help. I essentially want to paste the content of the second Message box into the word document. Dim ctl As Control Dim some As String Dim objExcel As Object Dim objWord As Object On Error Resume Next Set objExcel = GetObject(, "Excel.Application") If objExcel Is Nothing Then Set objExcel = CreateObject("Excel.Application")

问题 I know there are a few similar questions already on SO (1, 2, 3) but unfortunately my limited knowledge of JS doesn't allow me to extrapolate the scenarios to my personal use case, hence this question. I have the following piece of code which allows me to dynamically attach to and call from an object some functions, which works fine (available on JsFiddle): JavaScript : $.extend(true, window, { "MyPlugin": { "dynamicFunction": dummy_function } }); function dummy_function() { } function real

问题 I know there are a few similar questions already on SO (1, 2, 3) but unfortunately my limited knowledge of JS doesn't allow me to extrapolate the scenarios to my personal use case, hence this question. I have the following piece of code which allows me to dynamically attach to and call from an object some functions, which works fine (available on JsFiddle): JavaScript : $.extend(true, window, { "MyPlugin": { "dynamicFunction": dummy_function } }); function dummy_function() { } function real

问题 I'm trying to access objects properties inside an array in my code to render the text values of input boxes restored after a refresh from the local storage but for some reason when I try to run the for loop inside my appStart() function it gives me: "Uncaught TypeError: Cannot read property 'id' of undefined at appStart". Any insiights of why this happens and how to fix it will be greatly appreciated. const currentDayPlaceholder = $("#currentDay"); const timeInTimeBlocks = $(".input-group

问题 I am trying to update a value tit in three database records that is part of a jsonb array object to change the title of gid 1 to 'newTitle Group 1' from just 'group 1' using postgresql and python. create table groups (name varchar, grp jsonb) insert into groups (name, grp) values ('joe', [{"gid": "1", "ona": "joe", "tit": "group 1 "}, {"gid": "2", "ona": "harry", "tit": "tester1 group 2"}, {"gid": "3", "ona": "moe", "tit": "group 3"}]), ('harry', [{"gid": "1", "ona": "joe", "tit": "group 1 "}

问题 How come int[] arr = new int[5]; Object[] obj = arr; produces a compilation error while int[][] arr = new int[5][5]; Object[] obj = arr; doesn't? 回答1: int[] is an Object , so array of int[] is an array of Object . 来源： https://stackoverflow.com/questions/62435112/does-a-primitive-type-multi-dimensional-array-gets-casted-to-object-type-in-java