[Handsomeboy]

I have a problem and i dont know what is the real use of these words i know that they are used to show that an instance of
a class is from a special type but i wonder why should it be defined ?

[eclipsed4utoo]

some sample code...

// looping through all controls on a form
foreach (Control c in this.Controls)
{
     if (c is Button)
     {
          // I only want to deal with buttons
          Button btn = c as Button;
     }
}

this same code could be written like this without using AS and IS...

foreach (Control c in this.Controls)
{
     if (c.GetType() == typeof(Button))
     {
          // I only want to deal with buttons
          Button btn = (Button)c;
     }
}

It basically makes it more readable.

[FlashM]

There is one more difference between IS and AS.

1. If you compare two objects using IS keyword, your return value if TRUE/FALSE
2. If you convert some object to other object using AS keyword, your return value is NULL if converting is not successful.

Example:

Button btn = btnConvert;
foreach (Control c in this.Controls)
{
	if ((btn = c as Button) != null)
	{
		btn.Text = "updated";
	}
}

This post has been edited by FlashM: 03 December 2009 - 05:25 PM