[`OperationCanceledException`][1] is simply the base class for [`TaskCanceledException`][2] - so if you catch the former, you&#39;ll still catch the latter.

Some operations on concurrent collections throw just `OperationCanceledException`, as there aren&#39;t any actual *tasks* involved (at least as far as the public API is concerned). See [`BlockingCollection.TryTake`][3] for an example.

I would catch the `OperationCanceledException` just in case the task is cancelled due to an operation which itself just threw `OperationCanceledException` - you probably still want to treat that as &quot;just cancellation&quot;.

  [1]: http://msdn.microsoft.com/en-us/library/system.operationcanceledexception.aspx
  [2]: http://msdn.microsoft.com/en-us/library/system.threading.tasks.taskcanceledexception.aspx
  [3]: http://msdn.microsoft.com/en-us/library/dd381899.aspx

I&#39;m using Mocha to test a small module in my Express.js application. In this module, one of my functions returns an array. I want to test whether or not the array is correct for a given input. I am doing so like this:

    suite(&#39;getWords&#39;, function(){
        test(&quot;getWords should return list of numbers&quot;, function() {
            var result = [&#39;555&#39;, &#39;867&#39;, &#39;5309&#39;];
            assert.equal(result, getWords(&#39;555-867-5309&#39;));
        });
    });

When this runs, I get the following assertion error:
    
    AssertionError: [&quot;555&quot;,&quot;867&quot;,&quot;5309&quot;] == [&quot;555&quot;,&quot;867&quot;,&quot;5309&quot;]


However, when I change my test to an &lt;code&gt;assert.deepEqual&lt;/code&gt;, the test passes fine. I was wondering if it was a case of &lt;code&gt;==&lt;/code&gt; vs &lt;code&gt;===&lt;/code&gt;, but if I enter 

    [1,2,3] === [1,2,3]

into the node.js command line, I still get false. 

Why do arrays not compare the way other values do (e.g. &lt;code&gt;1 == 1&lt;/code&gt;)? and what is the difference between assert.equal and assert.deepEqual?



The difference between assert.equal and assert.deepEqual in Javascript testing with Mocha?

I&#39;ve got a class that has a couple of objects as member variables. I don&#39;t want the constructors for these members to be called when declared, so I&#39;m trying to hang onto a pointer to the object explicitly. I have no idea what I&#39;m doing.

I thought maybe I could do the following, where the constructor is called immediately when initializing the object member variable:

    class MyClass {
        public:
            MyClass(int n);
        private:
            AnotherClass another(100); // Construct AnotherClass right away!
    };

But I want the `MyClass` constructor to call the `AnotherClass` constructor. Here&#39;s what my code looks like:

### FIle *BigMommaClass.h*

    #include &quot;ThingOne.h&quot;
    #include &quot;ThingTwo.h&quot;

    class BigMommaClass {

            public:
                    BigMommaClass(int numba1, int numba2);

            private:
                    ThingOne* ThingOne;
                    ThingTwo* ThingTwo;
    };


### FIle *BigMommaClass.cpp*

    #include &quot;BigMommaClass.h&quot;

    BigMommaClass::BigMommaClass(int numba1, int numba2) {
            this-&gt;ThingOne = ThingOne(100);
            this-&gt;ThingTwo = ThingTwo(numba1, numba2);
    }

Here&#39;s the error I&#39;m getting when I try to compile:

```lang-none
g++ -Wall -c -Iclasses -o objects/BigMommaClass.o classes/BigMommaClass.cpp
In file included from classes/BigMommaClass.cpp:1:0:
classes/BigMommaClass.h:12:8: error: declaration of &#226;ThingTwo* BigMommaClass::ThingTwo&#226;
classes/ThingTwo.h:1:11: error: changes meaning of &#226;ThingTwo&#226; from &#226;class ThingTwo&#226;
classes/BigMommaClass.cpp: In constructor &#226;BigMommaClass::BigMommaClass(int, int)&#226;:
classes/BigMommaClass.cpp:4:30: error: cannot convert &#226;ThingOne&#226; to &#226;ThingOne*&#226; in assignment
classes/BigMommaClass.cpp:5:37: error: &#226;((BigMommaClass*)this)-&gt;BigMommaClass::ThingTwo&#226; cannot be used as a function
make: *** [BigMommaClass.o] Error 1
```

Am I using the right approach, but the wrong syntax? Or should I be coming at this from a different direction?






How can I initialize C++ object member variables in the constructor?

What is the difference between `OperationCanceledException` and `TaskCanceledException`? If I am using .NET 4.5 and using the `async`/`await` keywords, which one should I be looking to catch?

Difference between OperationCanceledException and TaskCanceledException?

<p>What is the difference between <code>OperationCanceledException</code> and <code>TaskCanceledException</code>? If I am using .NET 4.5 and using the <code>async</code>/<code>await</code> keywords, which one should I be looking to catch?</p>


I have done a project in C#.NET where my database file is an Excel workbook. Since the location of the connection string is hard coded in my coding, there is no problem for installing it in my system, but for other systems there is.

Is there a way to prompt the user to set a path once after the setup of the application is completed?

The answers I got was &quot;Use App.Config&quot;... can anyone tell what is this App.config and how to use it in my context here?

What is App.config in C#.NET? How to use it?

I have a value stored in variable of type `System.TimeSpan` as follows.

    System.TimeSpan storedTime = 03:00:00;

Can I re-store it in another variable of type `String` as follows?

    String displayValue = &quot;03:00 AM&quot;;

And if `storedTime` variable has the value of

    storedTime = 16:00:00;

then it should be converted to:

    String displayValue = &quot;04:00 PM&quot;;


Convert time span value to format &quot;hh:mm Am/Pm&quot; using C#

Following are the ways by which we can exit an application:

1. &lt;code&gt;Environment.Exit(0)&lt;/code&gt;
2. &lt;code&gt;Application.Exit()&lt;/code&gt;
3. &lt;code&gt;Form.Close()&lt;/code&gt;

What is the difference between these three methods and when to use each one?

Winforms: Application.Exit vs Environment.Exit vs Form.Close

Consider this, 

    Task task = new Task (async () =&gt;{
        await TaskEx.Delay(1000);
    });
    task.Start();
    task.Wait(); 

The call task.Wait() does not wait for the task completion and the next line is executed immediately, but if I wrap the async lambda expression into a method call, the code works as expected.

    private static async Task AwaitableMethod()
    {
        await TaskEx.Delay(1000);    
    }

then (updated according comment from svick)

    await AwaitableMethod(); 

can not await async lambda

I have added App.config file in my project.
I have created two settings from Project &gt; Properties &gt; Settings panel - 

[![enter image description here][2]][2]

I have noticed that when I am adding a setting, I can define scope as `User` or `Application`. -

 1. User
 2. Application

If I define setting as `User` it goes to`userSettings` section, &lt;br/&gt;
if I define setting as `Application` it goes to `applicationSettings` section

**App.config**

    &lt;configuration&gt;

        &lt;userSettings&gt;
            &lt;DemoApp.Properties.Settings&gt;
                &lt;setting name=&quot;MySetting1&quot; serializeAs=&quot;String&quot;&gt;
                    &lt;value&gt;Value1&lt;/value&gt;
                &lt;/setting&gt;
            &lt;/DemoApp.Properties.Settings&gt;
        &lt;/userSettings&gt;

        &lt;applicationSettings&gt;
            &lt;DemoApp.Properties.Settings&gt;
                &lt;setting name=&quot;MySetting2&quot; serializeAs=&quot;String&quot;&gt;
                    &lt;value&gt;Value2&lt;/value&gt;
                &lt;/setting&gt;
            &lt;/DemoApp.Properties.Settings&gt;
        &lt;/applicationSettings&gt;

    &lt;/configuration&gt;



But, these settings can be accessed in the same way from `.cs` -

**Code**

    string mySetting1 = DemoApp.Properties.Settings.Default.MySetting1;
    string mySetting2 = DemoApp.Properties.Settings.Default.MySetting2;


What is the difference between `User` and `Application` scope and under what circumstances one should choose between these two?


  [1]: http://i.stack.imgur.com/NsJaO.png
  [2]: http://i.stack.imgur.com/FHMTf.png

App.config: User vs Application Scope

How should an exception be raised in VB.NET?


How to raise an exception in VB.NET

`java.io.IOException` seems to be the most common type of exception, and coincidentally, it seems to also be the most ambiguous.

I keep seeing the `throws IOException` whenever writing with sockets, files, etc. I&#39;ve never actually had one fired on me, however, so I&#39;m wondering what it is that is supposed to fire the exception. The documentation isn&#39;t very helpful in explaining what&#39;s going on: 

&gt; Signals that an I/O exception of some sort has occurred. This class is the general class of exceptions produced by failed or interrupted I/O operations.

What are some instances where an IOException would be thrown, and how is it supposed to be used?



What throws an IOException in Java?

Try-catch is meant to help in the exception handling. This means somehow that it will help our system to be more robust: try to recover from an unexpected event. 

We suspect something might happen when executing and instruction (sending a message), so it gets enclosed in the try. If that something nearly unexpected happens, we can do something: we write the catch. I don&#39;t think we called to just log the exception. I thing the catch block is meant to give us the opportunity of recovering from the error.

Now, let&#39;s say we recover from the error because we could fix what was wrong. It could be super nice to do a re-try:

    try{ some_instruction(); }
    catch (NearlyUnexpectedException e){
       fix_the_problem();
       retry;
    }

This would quickly fall in the eternal loop, but let&#39;s say that the fix_the_problem returns true, then we retry. Given that there is no such thing in Java, how would YOU solve this problem? What would be your best design code for solving this?

This is like a philosophical question, given that I already know what I&#39;m asking for is not directly supported by Java.


How do you implement a re-try-catch?



    var err1 = Error(&#39;message&#39;);
    var err2 = new Error(&#39;message&#39;);


What&#39;s the difference? Looking at them in the chrome console, they look identical. Same properties on the object and the same `__proto__` chain. Almost seems like `Error` acts like a factory.

Which one is correct and why?

throw Error(&#39;msg&#39;) vs throw new Error(&#39;msg&#39;)

I have read many posts related to this issue, but couldn&#39;t find an answer.
I am trying to load a large amount of data from Excel into SQL Server.
Thousands of records. And I am getting this exception:

&gt; String or binary data would be truncated. The statement has been
&gt; terminated.

Obviously some values exceed the field size in the database.
The error comes from SQL Server AFIK.

----------

**My question - How could I possibly know what record and what field value caused this?**

There are no specific details in EF exception, except the one I mentioned.

Any help is appreciated.

Some asked for the code fragment, but it&#39;s actually very simple, the problem is not with the code:

    // employees is a List&lt;Employee&gt; collection loaded from Excel
    using (var context = new Entities())
    {
        employees.ForEach(e =&gt; context.Employee.AddObject(e));
        context.SaveChanges();
    }

Also the suggested approach to use **DbEntityValidationException** (which is only available in Entity Framework 5.0) is not working, the **catch** block didn&#39;t catch the exception.


    try
    {
        ImportData();
    }
    catch (DbEntityValidationException ex)
    {
        foreach (var item in ex.EntityValidationErrors)
        {
            //...
        }
    }

**The only solution that I found** so far is to use SQL Server Profiler, and define the following events to monitor:

![enter image description here][1]

![enter image description here][2]


  [1]: http://i.stack.imgur.com/mxJud.png
  [2]: http://i.stack.imgur.com/zfEu3.png

Now I can see the Email is too long.


EF Exception: String or binary data would be truncated. The statement has been terminated.?

We have this method:

    async Task&lt;int&gt; AccessTheWebAsync()
    { 
        HttpClient client = new HttpClient();

       Task&lt;string&gt; getStringTask = client.GetStringAsync(&quot;http://msdn.microsoft.com&quot;);

       // You can do work here that doesn&#39;t rely on the string from GetStringAsync.
       DoIndependentWork();

       string urlContents = await getStringTask;
       //The thing is that this returns an int to a method that has a return type of Task&lt;int&gt;
       return urlContents.Length;
    }

Does an implicit conversion occur between `Task&lt;int&gt;` and `int`? If not, then what is happening?  How is it implemented to work?

How does Task&lt;int&gt; become an int?

I have the following code,

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            button1.IsEnabled = false;

            var s = File.ReadAllLines(&quot;Words.txt&quot;).ToList(); // my WPF app hangs here
            // do something with s

            button1.IsEnabled = true;
        }

`Words.txt` has a ton of words which i read into the s variable, I am trying to make use of `async` and `await` keywords in C# 5 using `Async CTP Library` so the WPF app doesn&#39;t hang. So far I have the following code,

        private async void button1_Click(object sender, RoutedEventArgs e)
        {
            button1.IsEnabled = false;
            
            Task&lt;string[]&gt; ws = Task.Factory.FromAsync&lt;string[]&gt;(
                // What do i have here? there are so many overloads
                ); // is this the right way to do?
            
            var s = await File.ReadAllLines(&quot;Words.txt&quot;).ToList();  // what more do i do here apart from having the await keyword?
            // do something with s

            button1.IsEnabled = true;
        }

The goal is to read the file in async rather than sync, to avoid freezing of WPF app.

Any help is appreciated, Thanks!

How to Async Files.ReadAllLines and await for results?

I&#39;ve got an interface with some functions that return `Task`. Some of the classes that implement the interface do not have anything to await, while others might just throw - so the warnings are spurious and annoying.

Is it possible to suppress these warnings? E.g.:

&lt;!-- language: c# --&gt;

    public async Task&lt;object&gt; test()
    {
        throw new NotImplementedException();
    }

yields:

&gt; *warning CS1998: This async method lacks &#39;await&#39; operators and will run
&gt; synchronously. Consider using the &#39;await&#39; operator to await
&gt; non-blocking API calls, or &#39;await Task.Run(...)&#39; to do CPU-bound work
&gt; on a background thread.*

Suppress warning CS1998: This async method lacks &#39;await&#39;

I have the following code:

    for(var i = 0; i &lt; list.length; i++){
        mc_cli.get(list[i], function(err, response) {
            do_something(i);
        });
    }

`mc_cli` is a connection to a memcached database. As you can imagine, the callback function is asynchronous, thus it may be executed when the for loop already ended. Also, when calling in this way `do_something(i)` it always uses the last value of the for loop.

I tried with a closure in this way 

    do_something((function(x){return x})(i)) 
but apparently this is again using always the last value of the index of the for loop. 

I also tried declaring a function before the for loop like so:

    var create_closure = function(i) {
        return function() {
            return i;
        }
    }

and then calling 

    do_something(create_closure(i)())
but again without success, with the return value always being the last value of the for loop.

Can anybody tell me what am I doing wrong with closures? I thought I understood them but I can&#39;t figure why this is not working.

Calling an asynchronous function within a for loop in JavaScript

I&#39;m writing a Javascript script.
This script will probably be loaded asynchronously (AMD format).

In this script, I&#39;d like to do nothing important until the `window.load` event was fired.
So I listen to the window &quot;load&quot; event.

But if the script is loaded after window.load event... how can I know `window.load` was already fired?

And of course I don&#39;t want to add something in any other scripts (they are all loaded async, the problem is the same) :)


Edit :

Imagine an HTML doc with no Javascript in it at all.

Than someone insert in this doc a &lt;script&gt; tag, and this script tag loads my Javascript file.

This will execute my script.

How this script can know if window.load was already fired ?

No jQuery, not any script in the HTML doc before mine.

Is it possible to know ??

I found the `window.document.readystate` property. This property is for document &quot;ready&quot; event I guess, not for window &quot;load&quot;.
Is there anything similar for window &quot;load&quot; event ?

How to know if window &quot;load&quot; event was fired already

I want to send a request to a server and process the returned value:

    private static string Send(int id)
    {
        Task&lt;HttpResponseMessage&gt; responseTask = client.GetAsync(&quot;aaaaa&quot;);
        string result = string.Empty;
        responseTask.ContinueWith(x =&gt; result = Print(x));
        responseTask.Wait(); // it doesn&#39;t wait for the completion of the response task
        return result;
    }

    private static string Print(Task&lt;HttpResponseMessage&gt; httpTask)
    {
        Task&lt;string&gt; task = httpTask.Result.Content.ReadAsStringAsync();
        string result = string.Empty;
        task.ContinueWith(t =&gt;
        {
            Console.WriteLine(&quot;Result: &quot; + t.Result);
            result = t.Result;
        });
        task.Wait();  // it does wait
        return result;
    }

Am I using `Task` correctly? I don&#39;t think so because the `Send()` method returns `string.Empty` every time, while `Print` returns the correct value.

What am I doing wrong? How do I get the correct result from a server?

How do I wait until Task is finished in C#?

I&#39;m new to parallel programming. There are two classes available in .NET: `Task` and `Thread`. 

So, my questions are:

 * What is the difference between those classes? 
 * When is it better to use `Thread` over `Task` (and vice-versa)?

Task vs Thread differences

I have been doing some research on this but I am still VERY confused to say the least.

Can anyone give me a concrete example of when to use `Task` and when to use `Platform.runLater(Runnable);`? What exactly is the difference? Is there a golden rule to when to use any of these?

Also correct me if I&#39;m wrong but aren&#39;t these two &quot;Objects&quot; a way of creating another thread inside the main thread in a GUI (used for updating the GUI)?

Platform.runLater and Task in JavaFX

I have written a few C# apps that I have running via windows task scheduler. They are running successfully (as I can see from the log files that they are writing ) but windows task scheduler shows them returning a last run result of `0xE0434352`. Is there something I need to do in my C# application so that it returns a success code to the windows task scheduler?


My C# application is returning 0xE0434352 to Windows Task Scheduler but it is not crashing

I have an `async` method which returns no data:


    public async Task MyAsyncMethod()
    {
        // do some stuff async, don&#39;t return any data
    }

I&#39;m calling this from another method which returns some data:

    public string GetStringData()
    {
        MyAsyncMethod(); // this generates a warning and swallows exceptions
        return &quot;hello world&quot;;
    }

Calling `MyAsyncMethod()` without awaiting it causes a &quot;[Because this call is not awaited, the current method continues to run before the call is completed][1]&quot; warning in visual studio. On the page for that warning it states:

&gt; You should consider suppressing the warning only if you&#39;re sure that you don&#39;t want to wait for the asynchronous call to complete and that **the called method won&#39;t raise any exceptions**.

I&#39;m sure I don&#39;t want to wait for the call to complete; I don&#39;t need to or have the time to. **But the call *might* raise exceptions.**

I&#39;ve stumbled into this problem a few times and I&#39;m sure it&#39;s a common problem which must have a common solution.

**How do I safely call an async method without awaiting the result?**

# Update:

For people suggesting that I just await the result, this is code that is responding to a web request on our web service (ASP.NET Web API). Awaiting in a UI context keeps the UI thread free, but awaiting in a web request call will wait for the Task to finish before responding to the request, thereby increasing response times with no reason.


  [1]: http://msdn.microsoft.com/en-gb/library/hh965065.aspx

Content Type	Original Author	Original Content on Stackoverflow
Question	Peter	View Question on Stackoverflow
Solution 1 - C#	Jon Skeet	View Answer on Stackoverflow

Difference between OperationCanceledException and TaskCanceledException?

C# Problem Overview

C# Solutions

Solution 1 - C#

How can I initialize C++ object member variables in the constructor?

The difference between assert.equal and assert.deepEqual in Javascript testing with Mocha?

Attributions