Question

Possible Duplicate:
Direct casting vs 'as' operator?

Can any one tell the actual difference between snippet of code?

var unknown = (object)new List<string>();

// Snippet 1: as operator
foreach (var item in unknown as IList<int>) {
 // Do something with item
}


// Snippet 2: cast operator
foreach (var item in (IList<int>)unknown) {
 // Do something with item
}

Answer 1

as operator would not raise an error but cast will raise an error of InvalidCastException

From MSDN

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

expression as type

is equivalent to:

expression is type ? (type)expression : (type)null

except that expression is evaluated only once.

Note that the as operator only performs reference conversions and boxing conversions. The as operator cannot perform other conversions, such as user-defined conversions, which should instead be performed using cast expressions.