    var day = value.Date; // a DateTime that will just be whole days
    var time = value.TimeOfDay; // a TimeSpan that is the duration into the day

You can also use `DateTime.Now.ToString(&quot;yyyy-MM-dd&quot;)` for the date, and `DateTime.Now.ToString(&quot;hh:mm:ss&quot;)` for the time.

You can use **Instance.ToShortDateString()** for the date, &lt;br/&gt;
and **Instance.ToShortTimeString()**  for the time to get date and time from the same instance.

    var currentDateTime = dateTime.Now();
    var date=currentDateTime.Date;

With the .NET 6 which added `DateOnly` and `TimeOnly` structs it&#39;s not possible to get the date and time like this:

```
var dateTime = DateTime.Now;
var date = DateOnly.FromDateTime(dateTime);
var time = TimeOnly.FromDateTime(dateTime);
```

Docs:
- [DateOnly][1]
- [TimeOnly][2]


  [1]: https://docs.microsoft.com/en-us/dotnet/api/system.dateonly?view=net-6.0
  [2]: https://docs.microsoft.com/en-us/dotnet/api/system.timeonly?view=net-6.0

Sometimes you want to have your GridView as simple as:

      &lt;asp:GridView ID=&quot;grid&quot; runat=&quot;server&quot; /&gt;

You don&#39;t want to specify any BoundField, you just want to bind your grid to DataReader.
The following code helped me to format DateTime in this situation. 

    protected void Page_Load(object sender, EventArgs e)
    {
      grid.RowDataBound += grid_RowDataBound;
      // Your DB access code here...
      // grid.DataSource = cmd.ExecuteReader(CommandBehavior.CloseConnection);
      // grid.DataBind();
    }
    
    void grid_RowDataBound(object sender, GridViewRowEventArgs e)
    {
      if (e.Row.RowType != DataControlRowType.DataRow)
        return;
      var dt = (e.Row.DataItem as DbDataRecord).GetDateTime(4);
      e.Row.Cells[4].Text = dt.ToString(&quot;dd.MM.yyyy&quot;);
    }

The results shown here.
![DateTime Formatting][1]


  [1]: http://i.stack.imgur.com/f3gv8.jpg

I have learned that I can never access a private variable, only with a get-function in the class. But then why can I access it in the copy constructor?

Example:

    Field::Field(const Field&amp; f)
    {
      pFirst = new T[f.capacity()];
	
      pLast = pFirst + (f.pLast - f.pFirst);
      pEnd  = pFirst + (f.pEnd - f.pFirst);
      std::copy(f.pFirst, f.pLast, pFirst);
    }

My declaration:

    private:
      T *pFirst,*pLast,*pEnd;




Why can I access private variables in the copy constructor?

I would like to know the following:

 1. `Cloneable` means we can have a clone or a copy of objects, by
    implementing the `Cloneable` interface. What are the advantages and
    disadvantages of doing that?  
 2. How does the recursive cloning happen if the object is a
    composite object?


How does Cloneable work in Java and how do I use it?

I have a `DateTime` instance that has a Date and a Time. 
How do I extract only the date or only the time?

Getting Date or Time only from a DateTime Object

<p>I have a <code>DateTime</code> instance that has a Date and a Time.
How do I extract only the date or only the time?</p>


Given a list, which method is preferred to determine the number of elements inside?

    var myList = new List&lt;string&gt;();
    
    myList.Count
    myList.Count()

Lists: Count vs Count()

How do I check if a number is positive or negative in C#?

I have an array of strings:

    string[] remove = { &quot;a&quot;, &quot;am&quot;, &quot;p&quot;, &quot;pm&quot; };

And I have a textbox that a user enters text into. If they type any string in the `remove` array at the end of the text in the textbox, it should be removed. What is the easiest way to do this?

**EDIT** To clarify, I&#39;m making a time parser. When you give the function a string, it does its best to parse it into this format: `08:14pm` I have a textbox to test it. When the focus leaves the textbox, I need to get the text without the am/pm/a/p suffix so I can parse the number only segment.

C# removing substring from end of string

Lets say I have the following classes


    public class Animal { .... }

    public class Duck : Animal { ... }

    public class Cow : Animal { ... }

    public class Creator
    {
       public List&lt;T&gt; CreateAnimals&lt;T&gt;(int numAnimals)
       {
          Type type = typeof(T);
          List&lt;T&gt; returnList = new List&lt;T&gt;();
          //Use reflection to populate list and return
       }
    }

Now in some code later I want to read in what animal to create.

    Creator creator = new Creator();
    string animalType = //read from a file what animal (duck, cow) to create
    Type type = Type.GetType(animalType);
    List&lt;animalType&gt; animals = creator.CreateAnimals&lt;type&gt;(5);


Now the problem is the last line isn&#39;t valid. Is there some elegant way to do this then?

Calling a generic method with a dynamic type

In an MVC project I&#39;m creating I have the following `RequirePermissionAttribute` that gets put on any action that needs specific permissions (it&#39;s been simplified for this example):

    public class RequirePermissionAttribute : ActionFilterAttribute, IAuthorizationFilter
    {
        public Operation Permissions { get; set; }

        public RequirePermissionAttribute() { }

        public RequirePermissionAttribute(Operation permissions)
        {
            this.Permissions = permissions;
        }

        public bool AuthorizeCore(HttpContextBase httpContext)
        {
            IAuthorizationService authServ = new ASPNETAuthorizationService();
            return authServ.Authorize(httpContext);
        }

        public void OnAuthorization(AuthorizationContext filterContext)
        {
            Enforce.ArgNotNull(filterContext);

            if (this.AuthorizeCore(filterContext.HttpContext))
            {
                // code snipped.
            }
            else
            {
                // code snipped.
            }
        }
    }

So the problem obviously with this is that my authorize attribute has a dependency on the `ASPNETAuthorizationService` that I created. I can&#39;t go the constructor way since attributes are compile-time checked.

One thing to mention, I&#39;m using my own little IoC that I made and it doesn&#39;t have support for property injection (yet). Of course, if I did go the property injection route, I&#39;d have to add support for it (which I&#39;d have to do some research on).

What&#39;s the best way to inject something into an attribute class?

How to use dependency injection with an attribute?

I have a component that requires .NET 4.0 to run, how can my Inno Setup installer verify that it is installed, and if not, prompt the user to install it?

Inno Setup: Verify that .NET 4.0 is installed

If I declare this array...

    string[,] a = {
                      {&quot;0&quot;, &quot;1&quot;, &quot;2&quot;},
                      {&quot;0&quot;, &quot;1&quot;, &quot;2&quot;},
                      {&quot;0&quot;, &quot;1&quot;, &quot;2&quot;},
                      {&quot;0&quot;, &quot;1&quot;, &quot;2&quot;},
                  };

Then I can measure the length with

    a.Length

which is 12. How do I measure the dimension of the arrays within? If I try...

    a[0].Length

I get `Wrong number of indices inside []; expected 2`. What gives?

How do I find the size of a 2D array?

We&#39;ve seen plenty of questions about when and why to use `try`/`catch` and `try`/`catch`/`finally`. And I know there&#39;s definitely a use case for `try`/`finally` (especially since it is the way the `using` statement is implemented).

We&#39;ve also seen questions about &lt;a href=&quot;https://stackoverflow.com/questions/52312/what-is-the-real-overhead-of-try-catch-in-c&quot;&gt;the overhead of try/catch and exceptions&lt;/a&gt;.

The question I linked to, however, doesn&#39;t talk about the overhead of having JUST try-finally.

Assuming there are no exceptions from anything that happens in the `try` block, what&#39;s the overhead of making sure that the `finally` statements get executed on leaving the `try` block (sometimes by returning from the function)?

Again, I&#39;m asking ONLY about `try`/`finally`, no `catch`, no throwing of exceptions.

Thanks!

&lt;b&gt;EDIT:&lt;/b&gt; Okay, I&#39;m going to try to show my use case a little better.

Which should I use, `DoWithTryFinally` or `DoWithoutTryFinally`?

    public bool DoWithTryFinally()
    {
      this.IsBusy = true;
      
      try
      {
        if (DoLongCheckThatWillNotThrowException())
        {
          this.DebugLogSuccess();
          return true;
        }
        else
        {
          this.ErrorLogFailure();
          return false;
        }
      }
      finally
      {
        this.IsBusy = false;
      }
    }
    
    public bool DoWithoutTryFinally()
    {
      this.IsBusy = true;
      
      if (DoLongCheckThatWillNotThrowException())
      {
        this.DebugLogSuccess();
        
        this.IsBusy = false;
        return true;
      }
      else
      {
        this.ErrorLogFailure();
        
        this.IsBusy = false;
        return false;
      }
    }

This case is overly simplistic because there are only two return points, but imagine if there were four... or ten... or a hundred.

At some point I would want to use `try`/`finally` for the following reasons:

* Keep to DRY principles (especially as the number of exit points gets higher)
* If it turns out that I&#39;m wrong about my inner function not throwing an exception, then I want to make sure `this.Working` is set to `false`.

So hypothetically, given &lt;i&gt;performance concerns, maintainability, and DRY principles,&lt;/i&gt; for what number of exit points (especially if I &lt;i&gt;can&lt;/i&gt; assume that all inner exceptions are caught) do I want to incur whatever performance penalty is associated with `try`/`finally`?

&lt;b&gt;EDIT #2:&lt;/b&gt; I changed the name of `this.Working` to `this.IsBusy`. Sorry, forgot to mention this is multithreaded (though only one thread will ever actually call the method); other threads will be polling to see if the object is doing its work. The return value is merely success or failure for if the work went as expected.

Overhead of try/finally in C#?

I need to increment the month of a datetime value

    next_month = datetime.datetime(mydate.year, mydate.month+1, 1)

when the month is 12, it becomes 13 and raises error &quot;month must be in 1..12&quot;. (I expected the year would increment)

I wanted to use timedelta, but it doesn&#39;t take month argument.
There is [relativedelta][1] python package, but i don&#39;t want to install it just only for this.
Also there is a solution using [strtotime][2].

    time = strtotime(str(mydate));
    next_month = date(&quot;Y-m-d&quot;, strtotime(&quot;+1 month&quot;, time));

I don&#39;t want to convert from datetime to str then to time, and then to datetime; therefore, it&#39;s still a library too

Does anyone have any good and **simple** solution just like using timedelta?


  [1]: http://labix.org/python-dateutil
  [2]: http://pypi.python.org/pypi/timelib/0.2

How to increment datetime by custom months in python without using library

I am trying to convert a long value (*number of milliseconds elapsed from 1/1/1970 i.e. Epoch*) to time of format `h:m:s:ms`.

The long value I use as timestamp, I get from the field `timestamp` of a logging event from log4j.  

So far I&#39;ve tried the following and it fails:   
 

    logEvent.timeStamp/ (1000*60*60)
    TimeUnit.MILLISECONDS.toMinutes(logEvent.timeStamp)

but I get incorrect value:    

    1289375173771 for logEvent.timeStamp
    358159  for logEvent.timeStamp/ (1000*60*60) 
    21489586 for TimeUnit.MILLISECONDS.toMinutes(logEvent.timeStamp)

How do I go about this?

Convert timestamp in milliseconds to string formatted time in Java

In my application I am using Entity Framework. 

My Table

    -Article
    -period
    -startDate


I need records that match =&gt; `DateTime.Now &gt; startDate and (startDate + period) &gt; DateTime.Now`

I tried this code but its now working 

    Context.Article
        .Where(p =&gt; p.StartDate &lt; DateTime.Now)
        .Where(p =&gt; p.StartDate.AddDays(p.Period) &gt; DateTime.Now)

When I run my code the following exception occur
&gt;LINQ to Entities does not recognize the method &#39;System.DateTime AddDays(Double)&#39; method, and this method cannot be translated into a store expression.

Linq to EntityFramework DateTime

I have a feeling there is a simple/built-in way to do this but I can&#39;t find it.

I have a duration (in seconds) in an integer and I want to display it in a friendly format.

e.g. 3600 would be displayed as &quot;01:00:00&quot; or &quot;1 hour&quot; or something.

I can do it with `time_ago_in_words(Time.zone.now+3600)` but that feels like a bit of a hack, there is no reason to add/subtract from the current time just to format this value.  Is there a `duration_in_words()` or something?

Thanks

Convert duration to hours:minutes:seconds (or similar) in Rails 3 or Ruby

I have a DateTime variable:

    DateTime date = DateTime.Now;

I want to change the time part of a DateTime variable. But when I tried to access time part (hh:mm:ss) these fields are readonly.

Can&#39;t I set these properties?





Content Type	Original Author	Original Content on Stackoverflow
Question	Luke	View Question on Stackoverflow
Solution 1 - C#	Marc Gravell	View Answer on Stackoverflow
Solution 2 - C#	Joshua Smith	View Answer on Stackoverflow
Solution 3 - C#	Shail Nautiyal	View Answer on Stackoverflow
Solution 4 - C#	Muhammad Kashif	View Answer on Stackoverflow
Solution 5 - C#	DomenPigeon	View Answer on Stackoverflow
Solution 6 - C#	Alexander Chernosvitov	View Answer on Stackoverflow

Getting Date or Time only from a DateTime Object

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

Solution 4 - C#

Solution 5 - C#

Solution 6 - C#

How does Cloneable work in Java and how do I use it?

Why can I access private variables in the copy constructor?

Attributions