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

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

The object type is an alias for System.Object. The object type is used and shown as a keyword. I think it has something to do with legacy, but that's just a wild guess.

Have a look at this MSDN page for all details.

I prefer the use of the lowercased versions, but for no special reasons. Just because the syntax highlighting is different on these "basic" types and I don't have to use the shift key when typing...

One is an alias to the other. Its down to style.

string is an alias for global::System.String, and object for global::System.Object

Providing you have using System; in your class, String / string and Object / object are functionally identical and usage is a matter of style.

(EDIT: removed slightly misleading quote, as per Jon Skeet's comment)

string (with the lowercase "s") is the string type of the C# language and the type System.String is the implementation of string in the .NET framework.

In practise there is no difference besides stylistic ones.

EDIT: Since the above obviously wasn't clear enough, there is no difference between them, they are the same type once compiled. I was explaining the semantic difference that the compiler sees (which is just syntactic sugar, much like the difference between a while and for loop).

There are no difference. There is a number of types, called Primitive Data Types which are threated by compiler in style you mentioned.

Capitalized naming style is ISO naming rule. It's more general, common; forces the same naming rules for all objects in the source without exceptions such C# compiler has.

As of my knowledge, I know that it's a shortcut, it's easier to use string, rather than System.string.

But be careful there's a difference between String and string (c# is case sensitive)