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Using Statement


Defines a scope, outside of which an object or objects will be disposed.

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C#, through the .NET Framework common language runtime (CLR), automatically releases the memory used to store objects that are no longer required. The release of memory is non-deterministic; memory is released whenever the CLR decides to perform garbage collection. However, it is usually best to release limited resources such as file handles and network connections as quickly as possible.

The using statement allows the programmer to specify when objects that use resources should release them. The object provided to the using statement must implement theIDisposable interface. This interface provides the Dispose method, which should release the object’s resources.

A using statement can be exited either when the end of the using statement is reached or if an exception is thrown and control leaves the statement block before the end of the statement.

using System;

class C : IDisposable
{
     public void UseLimitedResource()
     {
         Console.WriteLine(“Using limited resource…”);
     }

     void IDisposable.Dispose()
     {
         Console.WriteLine(“Disposing limited resource.”);
     }
}

class Program
{
    static void Main()
    {
      using (C c = new C())
      {
        c.UseLimitedResource();
      }
      Console.WriteLine(“Now outside using statement.”);
      Console.ReadLine();
    }
}

Output:
Using limited resource…
Disposing limited resource.
Now outside using statement.

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