What's the point of “As” keyword in C#

Question

From the docs:

The as operator is like a cast except that it yields null on conversion failure instead of raising an exception. More formally, an exp

Answer 1

Maybe examples will help:

// Regular casting
Class1 x = new Class1();
Class2 y = (Class2)x; // Throws exception if x doesn't implement or derive from Class2

// Casting with as
Class2 y = x as Class2; // Sets y to null if it can't be casted.  Does not work with int to short, for example.

if (y != null)
{
  // We can use y
}

// Casting but checking before.
// Only works when boxing/unboxing or casting to base classes/interfaces
if (x is Class2)
{
  y = (Class2)x; // Won't fail since we already checked it
  // Use y
}

// Casting with try/catch
// Works with int to short, for example.  Same as "as"
try
{
  y = (Class2)x;
  // Use y
}
catch (InvalidCastException ex)
{
  // Failed cast
}