They have separate compilers (csc.exe for C# and vbc.exe for VB.Net) but they both get compiled into IL and then at run-time JIT compiles it into machine code.
Question 1 : can C# compiler compile VB.net code?
Answer 1: No it can't and you will see that in the below example. It gives an error if you try to do that as it looks for C# syntax.
Question 2: I think that's what they say in the book. Since it is two compilers, I feel it is not compatible
Answer 2: It doesn't say that you can compile VB code using C# but it says that you can mix languages in a single application like I did in the example below and still able to compile C# and VB (using their compilers).
See below example to understand how it works. I created a solution with a C# project with a C# class and a VB project with a VB class. You should not mix C# and VB classes in same project as it will ignore the vb file if its a C# project during build.
Content of ClassCSharp.cs:
namespace ClassLibraryCSharp
{
public abstract class ClassCSharp
{
public int MyProperty { get; set; }
protected abstract void Test();
}
}
Content of ClassVBInCSharp.vb in C# ClassLibrary. See how I can inherit from a C# class and also access its properties and override the method.
Namespace ClassLibraryVB
Public Class ClassVBInCSharp
Inherits ClassCSharp
Property Test2 As Integer
Protected Overrides Sub Test()
Test2 = MyBase.MyProperty
End Sub
End Class
End Namespace
See below commands I ran:
vbc.exe /reference:"ClassLibraryCSharp.dll" /target:library /out:"ClassLibraryCSharpVbVersion.dll" "ClassVBInCSharp.vb"
Microsoft (R) Visual Basic Compiler version 12.0.20806.33440
Copyright (c) Microsoft Corporation. All rights reserved.
See above VB Compiler is used to compile vb class.
csc.exe /reference:"ClassLibraryCSharp.dll" /target:library /out:"ClassLibraryCSharpVersion.dll" "ClassVBInCSharp.vb"
Microsoft (R) Visual C# Compiler version 4.0.30319.33440 for Microsoft (R) .NET Framework 4.5
Copyright (C) Microsoft Corporation. All rights reserved.
ClassLibrary1\ClassVBInCSharp.vb(1,1): error CS
0116: A namespace cannot directly contain members such as fields or methods
See above if I try to use C# Compiler to compile vb class it throws an error as its looking for C# syntax.
