When does it matter whether you use int versus Int32, or string versus String?
In C#, the keywords for built-in types are simply aliases for corresponding types in the System namespace.
Generally, it makes no difference whether you use a keyword (such as int ) or an identifier (such as Int32 ) to refer to a built-in type. But there's an exception to everything, so my question in two parts is:
C# doesn't require you to use one or the other as they are equivalent. It is a personal preference and coding convention. So use the one that seems more readable to you and your team. Just one advice: be consistent: do not use an alias in half of your codebase and the full type name in the second half.
string is an alias for the type System.String , and int is an alias for System.Int32 . Therefore, use to your preference.
A using alias directive cannot use a keyword as the type name (but can use keywords in type argument lists):
using Handle = int; // error
using Handle = Int32; // OK
using NullableHandle = Nullable<int>; // OK
The underlying type of an enum must be specified using a keyword:
enum E : int { } // OK
enum E : Int32 { } // error
The expressions (x)+y , (x)-y , and (x)*y are interpreted differently depending on whether x is a keyword or an identifier:
(int)+y // cast +y (unary plus) to int
(Int32)+y // add y to Int32; error if Int32 is not a variable
(Int32)(+y) // cast +y to Int32
(int)-y // cast -y (unary minus) to int
(Int32)-y // subtract y from Int32; error if Int32 is not a variable
(Int32)(-y) // cast -y to Int32
(int)*y // cast *y (pointer indirection) to int
(Int32)*y // multiply Int32 by y; error if Int32 is not a variable
(Int32)(*y) // cast *y to Int32
上一篇: 将两个列表结合在一起