9.11. Common typing with other .NET languages

Adherence to the CTS enables all .NET languages to interoperate. Having a common type system enables codes from different languages to integrate seamlessly. You can easily pass a variable of a common type between methods written in different .NET languages. You can even write a class in C# which inherits from a class written in VB .NET. One factor that makes such interoperability possible is the adherence of each .NET programming language to the CTS.

The CTS specifies a set of common types shared by all the .NET programming languages. You can either use the full .NET framework type name or the C# alias ^[9] in your C# programs. Table 9.6 shows the available C# aliases for types defined in the CTS.

^[9] Needless to say, this will be the more popular (and recommended) choice. Who would prefer to write 'System.String' instead of 'string'?

This implies that the following two statements are equivalent, except that the first is easier to read:

						ulong temp = 99L; // usage of C# alias
System.UInt64 temp = 99L; // usage of full type name

Other .NET languages may have their own aliases for the .NET types too, so that writing in those languages will be more natural. For example, for VB .NET developers, their familiar Integer type maps to System.Int32. And for J# developers, J#'s int type also maps to System.Int32. VB .NET's Integer type and J#'s int type refer to exactly the same type as C#'s int – a 32-bit signed integer.

Additional notes:

• All the types listed in Table 9.6, except object and string, are referred to as simple types. Simple types are value types – on the other hand, object and string are reference types.

  Table 9.6. C# aliases for BCL types

  C# alias	.NET framework type
  bool	System.Boolean
  byte	System.Byte
  sbyte	System.SByte
  char	System.Char
  decimal	System.Decimal
  double	System.Double
  float	System.Single
  int	System.Int32
  uint	System.UInt32
  long	System.Int64
  ulong	System.UInt64
  long	System.Int64
  ulong	System.UInt64
  object	System.Object
  short	System.Int16
  ushort	System.UInt16
  string	System.String

  
  

• To display the actual type a C# variable represents, use the GetType() ^[10] method of System.Object. For example, the following statement displays the system alias that represents the type of myVariable:

  ^[10] System.Object is the superclass of all C# classes (very much like java.lang.Object). As such, all methods declared within are inherited to every C# class – GetType() is one such method.

  Console.WriteLine(myVariable.GetType());