object keyword is nothing more than a shortcut for System.Object, which is the root type in the C# class hierarchy. However, not everything in C# derives from object, you can
get more information on this from Eric Lippert’s blog article http://blogs.msdn.com/ericlippert/archive/2009/08/06/not-everything-derives-from-object.aspx
.
Even if we know an object type variable stores an int value, we still have to first convert the object variable to int type and then do int-type operation on it.
Otherwise, the compiler will detect it breaks the rule.
object o = 10;
o = o+10; //cannot compile for “operator + cannot apply to operands of type object and int”
In C# 4.0, the dynamic is introduced. In compile time, we do not need to convert the dynamic type variable to the specified type and then perform the operation.
dynamic dyn = 10;
dyn = dyn + 10; //compile OK.
dynamic you tell the compiler that the type of an object can be known only at run time, and the compiler doesn’t try to interfere. As a result, you can write
less code. And I want to emphasize that this is no more dangerous than using the original object keyword. However, it is not less dangerous either, so all the type-checking techniques that you need to use when operating with objects (such as reflection) have
to be used for dynamic objects as well.
A detailed blog article about this:
http://blogs.msdn.com/csharpfaq/archive/2010/01/25/what-is-the-difference-between-dynamic-and-object-keywords.aspx
For more FAQ about Visual C#
General, please see
Visual C# General FAQ
