As of .NET 2, if you don&#39;t tweak the configuration? Nothing.

Before then, or with some config tweak I can&#39;t remember precisely, there was the possibility of an exception being thrown from unmanaged code which *didn&#39;t* get converted into an `Exception`-compatible object.

Note that there&#39;s another option in between, where you specify the type but no variable:

    catch (Exception)
    {
       ...
    }

Personally I&#39;d be very wary of catching an exception without even *logging* it. It may be required if you&#39;re calling a boneheaded API, but it&#39;s generally best avoided.

I think they are the same. But the second case raised a compiler warning because you declare an exception you didn&#39;t use. I rather like the first one because you say explicitly that you don&#39;t use the exception. There is also a third one

    catch (Exception)
    {
        //do something
    }

if you want to specify the type of exception but doesn&#39;t care about the exception itself.

Generally you should catch specific errors first. 

But if you go for catching a general `Exception` like you do I&#39;d say use the second case:

    catch (Exception ex)
    {
         MessageBox.Show(&quot;Error.&quot;);
         //we never use ex, so is it better to use catch without arguments?
    }

this can help you with debbuging since the variable contains the stack trace, exception message...etc. Which you can use for logging the error or something that will help you preventing it.

Be very carefull using this approach, though:

    MessageBox.Show(&quot;Error.&quot;);

Not keeping track of your errors somewhere(like a log file) can cause a really big mess.

In your second example you can reference exception data, like the stack trace, source, etc. It also gives a general message that is sometimes helpful. It tells you WHY you suffered an exception which is important when debugging.

Some exception can not be `catch(Exception)` catched.

Below excecption in mono on linux, should catch without parameter.

Otherwise runtime will ignore `catch(Exception)` statment.

    System.Reflection.ReflectionTypeLoadException: The classes in the module cannot be loaded.

If you encounter the problem like that, try remove parameter of `catch` statement, log the context vars to find out error cause.

P.S. I don&#39;t know how on windows, the program run in windows is normal.

A simple comparison of two double values in Java creates some problems. Let&#39;s consider the following simple code snippet in Java.

    package doublecomparision;

    final public class DoubleComparision 
    {
        public static void main(String[] args) 
        {
            double a = 1.000001;
            double b = 0.000001;

            System.out.println(&quot;\n&quot;+((a-b)==1.0));
        }
    }


----------
The above code appears to return `true`, the evaluation of the expression `((a-b)==1.0)` but it doesn&#39;t. It returns `false` instead because the evaluation of this expression is `0.9999999999999999` which was actually expected to be `1.0` which is not equal to `1.0` hence, the condition evaluates to boolean `false`. What is the best and suggested way to overcome such a situation?

How to compare two double values in Java?

I have many .mp3 files stored in res/raw folder.

I am getting URI of .mp3 file using following code.

    Uri.parse(&quot;android.resource:///com.my.android.sharesound/&quot;+resId);

This returns : `android.resource:///com.my.android.sharesound/2130968609`

Now I am using this URI in creating Share Intent

        shareIntent.putExtra(Intent.EXTRA_STREAM,Uri.parse(&quot;android.resource://com.my.android.sharesound/&quot;+resId));
        startActivity(Intent.createChooser(shareIntent,&quot;Share Sound&quot;);

When i select any Mail application eg. Gmail or YahooMail from the Share Intent, the mp3 file attached successfully. But it shows that 2130968609(as an attachment)

i dont want resourceId(2130968609) to appear. 

I want to display fileName.mp3

How can i do that? Am i missing something ?

OR

Is there any other way to attach .mp3 file stored in res/raw to mail via Share Intent.

Get URI of .mp3 file stored in res/raw folder in android

What is the difference between:

    catch
    {
        MessageBox.Show(&quot;Error.&quot;);
    }

and:

    catch (Exception ex)
    {
        MessageBox.Show(&quot;Error.&quot;);
        //we never use ex, so is it better to use catch without arguments?
    }

Using catch without arguments

What is the difference between:
<pre><code class="hljs language-arduino">catch
{
 MessageBox.Show("Error.");
}
</code></pre>
and:
<pre><code class="hljs language-php">catch (Exception ex)
{
 MessageBox.Show("Error.");
 //we never use ex, so is it better to use catch without arguments?
}
</code></pre>

I am looking for a way to call a method on a new thread (using C#).

For instance, I would like to call `SecondFoo()` on a new thread. However, I would then like to have the thread terminated when `SecondFoo()` finishes.

I have seen several examples of threading in `C#`, but none that apply to this specific scenario where I need the spawned thread to terminate itself. Is this possible?

**How can I force the spawned thread running `Secondfoo()` to terminate upon completion?**

Has anyone come across any examples of this?


C# Call a method in a new thread

Is there a short way to create the getter and setter in c#?

    public string fname {get; set;} 

Is there short hand to generate `{get; set;}`?

C# shortcut or shorthand getter setter

I am trying to extend the JSON.net example given here 
http://james.newtonking.com/projects/json/help/CustomCreationConverter.html

I have another sub class deriving from base class/Interface

	public class Person
	{
		public string FirstName { get; set; }
		public string LastName { get; set; }
	}
	
	public class Employee : Person
	{
		public string Department { get; set; }
		public string JobTitle { get; set; }
	}
	
	public class Artist : Person
	{
		public string Skill { get; set; }
	}

	List&lt;Person&gt; people  = new List&lt;Person&gt;
	{
		new Employee(),
		new Employee(),
		new Artist(),
	};


How do I deserialize following Json back to List&lt; Person &gt;

	[
	  {
		&quot;Department&quot;: &quot;Department1&quot;,
		&quot;JobTitle&quot;: &quot;JobTitle1&quot;,
		&quot;FirstName&quot;: &quot;FirstName1&quot;,
		&quot;LastName&quot;: &quot;LastName1&quot;
	  },
	  {
		&quot;Department&quot;: &quot;Department2&quot;,
		&quot;JobTitle&quot;: &quot;JobTitle2&quot;,
		&quot;FirstName&quot;: &quot;FirstName2&quot;,
		&quot;LastName&quot;: &quot;LastName2&quot;
	  },
	  {
		&quot;Skill&quot;: &quot;Painter&quot;,
		&quot;FirstName&quot;: &quot;FirstName3&quot;,
		&quot;LastName&quot;: &quot;LastName3&quot;
	  }
	]

I don&#39;t want to use TypeNameHandling JsonSerializerSettings. I am specifically looking for custom JsonConverter implementation to handle this. The documentation and examples around this are pretty sparse on the net. I can&#39;t seem to get the the overridden ReadJson() method implementation in JsonConverter right.

How to implement custom JsonConverter in JSON.NET?

I want to read a text file line by line. I wanted to know if I&#39;m doing it as efficiently as possible within the .NET C# scope of things.

This is what I&#39;m trying so far:

    var filestream = new System.IO.FileStream(textFilePath,
                                              System.IO.FileMode.Open,
                                              System.IO.FileAccess.Read,
                                              System.IO.FileShare.ReadWrite);
    var file = new System.IO.StreamReader(filestream, System.Text.Encoding.UTF8, true, 128);

    while ((lineOfText = file.ReadLine()) != null)
    {
        //Do something with the lineOfText
    }


What&#39;s the fastest way to read a text file line-by-line?

Does anyone stick to any rules (or are you forced to stick to any rules by your employer?) when choosing to use either LINQ query syntax or a Lambda expression inside one of the LINQ extension methods? This applies to any Entities, SQL, objects, anything.

At our workplace, my boss doesn&#39;t like lambda at all and he&#39;d use the query syntax for anything, which in some cases, I find are less readable.

    var names = collection.Select(item =&gt; item.Name);

    var names = from item in collection
                select item.Name;

Maybe when adding a condition, the Lambda I find gets a little messy, where the 

    var names = collection.Where(item =&gt; item.Name == &quot;Fred&quot;)
                          .Select(item =&gt; item.Name);

    var names = from item in collection
                where item.Name == &quot;Fred&quot;
                select item.Name;
    
Just out of interest: how does the compiler treat this one? Does anyone know how the above LINQ query will compile into lambda? Will the `Name` property be called for each element? Could we do this instead and potentially improve the performance? Would this mean lambda is slightly more controllable in terms of performance?

    var names = collection.Select(item =&gt; item.Name)
                          .Where(name =&gt; name == &quot;Fred&quot;);

Certainly when we start using more and more expressions, the lambda gets messy and I&#39;d start to use the query syntax here.

    var names = collection.Where(item =&gt; item.Name == &quot;Fred&quot;)
                          .OrderBy(item =&gt; item.Age)
                          .Select(item =&gt; item.Name);

    var names = from item in collection
                where item.Name == &quot;Fred&quot;
                order by item.Age
                select item.Name;

There are also a few things that I find can&#39;t be done with the query syntax. Some of them you&#39;d think would be really simple (particularly aggregate functions), but no, you have to add one of the LINQ extension methods to the end, which imo, look neater with a lambda expression.

    var names = collection.Count(item =&gt; item.Name == &quot;Fred&quot;);

    var names = (from item in collection
                where item.Name == &quot;Fred&quot;
                select item).Count()

Even for some of the simple lambda chains, [ReSharper][1] is suggesting I convert them to LINQ querys.

Can anyone else add to this? Does anyone have their own little rules or does their company suggest/force the use of one?


  [1]: http://www.jetbrains.com/resharper/

LINQ - Query syntax vs method chains &amp; lambda

I&#39;ve read a few other SO questions about `tryCatch` and cuzzins, as well as the documentation:

 - https://stackoverflow.com/questions/2622777/exception-handling-in-r
 - https://stackoverflow.com/questions/2158780/r-catching-an-error-and-then-branching-logic
 - https://stackoverflow.com/questions/3903157/how-can-i-check-whether-a-function-call-results-in-a-warning
 - [Problems with Plots in Loop][1]

but I still don&#39;t understand.

I&#39;m running a loop and want to skip to `next` if any of a few kinds of errors occur:

    for (i in 1:39487) {

      # EXCEPTION HANDLING
      this.could.go.wrong &lt;- tryCatch(
                               attemptsomething(),
                               error=function(e) next
                             )
      so.could.this &lt;- tryCatch(
                         doesthisfail(),
                         error=function(e) next
                       )

      catch.all.errors &lt;- function() { this.could.go.wrong; so.could.this; }
      catch.all.errors;


      #REAL WORK
      useful(i); fun(i); good(i);

      }  #end for



*(by the way, there is no documentation for `next` that I can find)*


When I run this, `R` honks:

    Error in value[[3L]](cond) : no loop for break/next, jumping to top level

What basic point am I missing here? The `tryCatch`&#39;s are clearly within the `for` loop, so why doesn&#39;t `R` know that?


  [1]: http://r.789695.n4.nabble.com/problems-with-plots-in-loop-corrected-Email-td3597451.html

Use tryCatch skip to next value of loop upon error?

If an Exception happens within a using statement does the object still get disposed?

The reason why I&#39;m asking is because I&#39;m trying to decide on whether to put a try caught around the whole code block or within the inner using statement. Bearing in mind certain exceptions are being re-thrown by design within the catch block.

    using (SPSite spSite = new SPSite(url))
    {
       // Get the Web
       using (SPWeb spWeb = spSite.OpenWeb())
       {
           // Exception occurs here
       }
    }

If an Exception happens within a using statement does the object still get disposed?

I ran a sample program and indeed destructors for stack-allocated objects are called, but is this guaranteed by the standard?

Are destructors called after a throw in C++?

Is there any overhead in Java for using a **try/catch** block, as opposed to an **if block** (assuming that the enclosed code otherwise does not request so)?

For example, take the following two simple implementations of a &quot;safe trim&quot; method for strings:

    public String tryTrim(String raw) {
        try {
            return raw.trim();
        } catch (Exception e) {
        }
        return null;
    }

    public String ifTrim(String raw) {
        if (raw == null) {
            return null;
        }
        return raw.trim();
    }

If the `raw` input is only rarely `null`, **is there any performance difference** between the two methods?

Furthermore, **is it a good programming pattern** to use the `tryTrim()` approach for simplifying the layout of code, especially when many **if blocks** checking rare error conditions can be avoided by enclosing the code in one try/catch block?

For example, it is a common case to have a method with `N parameters`, which uses `M &lt;= N` of them near its start, failing quickly and deterministically if any such parameter is &quot;invalid&quot; (e.g., a null or empty string), without affecting the rest of the code.

In such cases, instead of having to write `k * M` **if blocks** (where `k` is the average number of checks per parameter, e.g. `k = 2` for null or empty strings), a **try/catch** block would significantly shorten the code and a 1-2 line comment could be used to explicitly note the &quot;unconventional&quot; logic.

Such a pattern would also speed up the method, especially if the error conditions occur rarely, and it would do so without compromising program safety (assuming that the error conditions are &quot;normal&quot;, e.g. as in a string processing method where null or empty values are acceptable, albeit seldom in presence).


Java if vs. try/catch overhead

I wrote some code for testing the impact of try-catch, but seeing some surprising results.

    static void Main(string[] args)
    {
        Thread.CurrentThread.Priority = ThreadPriority.Highest;
        Process.GetCurrentProcess().PriorityClass = ProcessPriorityClass.RealTime;

        long start = 0, stop = 0, elapsed = 0;
        double avg = 0.0;

        long temp = Fibo(1);

        for (int i = 1; i &lt; 100000000; i++)
        {
            start = Stopwatch.GetTimestamp();
            temp = Fibo(100);
            stop = Stopwatch.GetTimestamp();

            elapsed = stop - start;
            avg = avg + ((double)elapsed - avg) / i;
        }

        Console.WriteLine(&quot;Elapsed: &quot; + avg);
        Console.ReadKey();
    }

    static long Fibo(int n)
    {
        long n1 = 0, n2 = 1, fibo = 0;
        n++;

        for (int i = 1; i &lt; n; i++)
        {
            n1 = n2;
            n2 = fibo;
            fibo = n1 + n2;
        }

        return fibo;
    }

On my computer, this consistently prints out a value around 0.96..

When I wrap the for loop inside Fibo() with a try-catch block like this:

    static long Fibo(int n)
    {
        long n1 = 0, n2 = 1, fibo = 0;
        n++;

        try
        {
            for (int i = 1; i &lt; n; i++)
            {
                n1 = n2;
                n2 = fibo;
                fibo = n1 + n2;
            }
        }
        catch {}

        return fibo;
    }

Now it consistently prints out 0.69... -- it actually runs faster! But why?

Note: I compiled this using the Release configuration and directly ran the EXE file (outside Visual Studio).

EDIT: [Jon Skeet&#39;s *excellent* analysis][1] shows that try-catch is somehow causing the x86 CLR to use the CPU registers in a more favorable way in this specific case (and I think we&#39;re yet to understand why). I confirmed Jon&#39;s finding that x64 CLR doesn&#39;t have this difference, and that it was faster than the x86 CLR. I also tested using `int` types inside the Fibo method instead of `long` types, and then the x86 CLR was as equally fast as the x64 CLR.


----------


**UPDATE:** It looks like this issue has been fixed by Roslyn. Same machine, same CLR version -- the issue remains as above when compiled with VS 2013, but the problem goes away when compiled with VS 2015. 


  [1]: https://stackoverflow.com/a/8928476/282110

Content Type	Original Author	Original Content on Stackoverflow
Question	petko_stankoski	View Question on Stackoverflow
Solution 1 - C#	Jon Skeet	View Answer on Stackoverflow
Solution 2 - C#	Iesvs	View Answer on Stackoverflow
Solution 3 - C#	TheBoyan	View Answer on Stackoverflow
Solution 4 - C#	Jeff LaFay	View Answer on Stackoverflow
Solution 5 - C#	IlPADlI	View Answer on Stackoverflow

Using catch without arguments

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

Solution 4 - C#

Solution 5 - C#

Get URI of .mp3 file stored in res/raw folder in android

How to compare two double values in Java?

Attributions