what is the significance of using in c#?

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Hello,

I came across a pseudo code yesterday :

string s;
using(new ClassA("hello"))
{
for(int i =0 ; i < some_count; i++)
s = "a";
s=null;
}

Class ClassA(string data) : IDisposable
{

public void Dispose()
{
/////do some disposal

}
}

can someone please explain me the significance of Using keyword here?

Thanks and Regards

Posted 2-Jan-14 19:35pm

Rahul VB

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Rahul VB 3-Jan-14 1:38am

- and one more thing to add up: i also want to know that an object has been garbage collected, like i wrote above "s = null", i want to know that s has been garbage collected, how to achieve that?

Thanks

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*dan!sh* · Accepted Answer · 2014-01-02T19:42:00

Solution 2

CP has a great article base to help with questions like these. Take a look at Understanding the 'using' statement in C#[^] article.

Posted 2-Jan-14 19:42pm

dan!sh

ArunRajendra · Accepted Answer · 2014-01-02T19:42:00

Solution 1

Check this link

http://msdn.microsoft.com/en-us/library/yh598w02.aspx[^]

Posted 2-Jan-14 19:42pm

ArunRajendra

Sibasisjena · Accepted Answer · 2014-01-02T19:42:00

Solution 3

Please refer the following links :
Link1[^]
Link2[^]
Link3[^]

Posted 2-Jan-14 19:42pm

Sibasisjena

Gitanjali Singh · Accepted Answer · 2014-01-02T20:40:00

Solution 4

The reason for the "using" statement is to ensure that the object is always disposed correctly, and it doesn't require explicit code to ensure that this happens.When we use using in our code, no need to dispose the object of class.

Posted 2-Jan-14 20:40pm

Gitanjali Singh

Comments

Rahul VB 3-Jan-14 2:53am

Hello Mam,
If i add a code:

static void Main(string[] args)
{
Class1 c;
using (c = new Class1())
{
c.hello();

}

Console.ReadLine();

}

class Class1:IDisposable
{
public void hello()
{
Console.WriteLine("hello");

}

public void Dispose()
{

Console.WriteLine("disposed");
}

}

The output is :
hello
dispose

My doubt is that i have not called the Dispose() explicitly, but CLR still executes it. If i would have not implemented the IDisposable interface explicitly then CLR would have done it automatically, because it is the job of the CLR.

Is this true for all standard Interfaces?

Thanks and Regards

Gitanjali Singh 3-Jan-14 3:16am

As per http://www.codeproject.com/KB/cs/tinguusingstatement.aspx, the .NET CLR converts

using (MyResource myRes = new MyResource())
{
myRes.DoSomething();
}
to

{ // limits scope of myRes
MyResource myRes= new MyResource();
try
{
myRes.DoSomething();
}
finally
{
// Check for a null resource.
if (myRes!= null)
// Call the object's Dispose method.
((IDisposable)myRes).Dispose();
}
}

Note that it's not necessarily a matter of the object being disposed correctly, but more of whether it is disposed in a timely manner. Objects implementing IDisposable which hold on to unmanaged resources like streams and file handles will also implement a finalizer that will ensure that Dispose is called during garbage collection. The problem is that GC might not happen for a relatively long time. using makes sure that Dispose is called once you're through with objects.

Rahul VB 3-Jan-14 4:29am

Hello Mam,
Thanks, very interesting.
-Rahul

Gitanjali Singh 3-Jan-14 6:08am

If it helps you ,accept it as solution :)

TrushnaK · Accepted Answer · 2014-01-02T21:14:00

Solution 5

The using block helps manage resources. Conceptually it protects the whole system's resources by specifying the scope of the usage of the resource. The using statement is combined with a type that implements IDisposable.

refer below links:-
This[^]
This[^]

Posted 2-Jan-14 21:14pm

TrushnaK