c#: difference between "System.Object" and "object"

Question

In C#, is there any difference between using System.Object in code rather than just object, or System.String rather than string and so on? Or is it just a matter of style?

Is there a reason why one form is preferrable to the other?

Answer 1

string is an alias for global::System.String. It's simply syntactic sugar. The two are exactly interchangable in almost all cases, and there'll be no difference in the compiled code.

Personally I use the aliases for variable names etc, but I use the CLR type names for names in APIs, for example:

public int ReadInt32() // Good, language-neutral  public int ReadInt() // Bad, assumes C# meaning of "int" 

(Note that the return type isn't really a name - it's encoded as a type in the metadata, so there's no confusion there.)

The only places I know of where one can be used and the other can't (that I'm aware of) are:

• nameof prohibits the use of aliases
• When specifying an enum base underlying type, only the aliases can be used