C# Frequently Asked Questions : C#/VB.NET Equivalents

How to keep a local variable in scope across a try and catch block?

CSharpFAQ — Fri, 13 Aug 2004 01:33:00 GMT

The following code won't work, because conn goes out of scope before you enter the catch block.

try

{

Connection conn = new Connection();

conn.Open();

}

catch

{

if (conn != null) conn.Close();

}

The fix is simple - just declare conn before entering the try block

Connection conn = null; // Note the assignment to null to avoid error CS0165 - Use of possibly unassigned local variable 'conn'.

try

{

conn = new Connection();

conn.Open();

}

catch

{

if (conn != null) conn.Close();

}

Of course, for this particular example, you could wrap the Connection class in one that implements IDisposable (if it does not already), so that you could then use a using statement instead of extending the scope of the local.

[author: SantoshZ]

Where can I get a full comparison between C# and VB.NET?

CSharpFAQ — Fri, 12 Mar 2004 10:31:00 GMT

Microsoft provides a very full language equivalents page which compares not only C# and VB.NET, but also other languages targeted at the .NET framework. It looks at the equivalent concepts, keywords, types, operators etc. A very valuable resource when you're trying to read or write code in a language which isn't your preferred one.

[Author: Jon Skeet]

Is there an equivalent of `MyClass`?

CSharpFAQ — Fri, 12 Mar 2004 10:30:00 GMT

No, C# doesn't have an equivalent of VB.NET's MyClass keyword. If you want to guarantee not to call an overridden version of a method, you need to make it non-virtual in the first place.

[Author: Jon Skeet]

What do I use instead of `addressof`?

CSharpFAQ — Fri, 12 Mar 2004 10:29:00 GMT

To create delegate instances in C#, you just specify the delegate type, the method, and (if you want to create a delegate targetting a different instance or type from the current one) the target. For instance, each of these creates a ThreadStart delegate:

ThreadStart x1 = new ThreadStart(SomeInstanceMethod);
ThreadStart x2 = new ThreadStart(AnotherType.SomeStaticMethod);
ThreadStart x3 = new ThreadStart(someVariable.SomeInstanceMethod);

[Author: Jon Skeet]

How do I get the rightmost part of a string, as with the VB `Right` function?

CSharpFAQ — Fri, 12 Mar 2004 10:28:00 GMT

Use String.Substring. Assuming that x is a string of length at least n, to get the last n characters, you would use x.Substring(x.Length-n).

Note that the above assumes that the string is at least n characters long. For a more robust version, you might use something like: x.Length < n ? x.Substring(x.Length-n) : x.

[Author: Jon Skeet]

What are the equivalents of `Me` and `MyBase`?

CSharpFAQ — Fri, 12 Mar 2004 10:27:00 GMT

Me in C# is this, and MyBase in C# is base. To access normal members, just use this.memberName or base.memberName. For information about chaining constructors together, see my article on constructors.

[Author: Jon Skeet]

What's the equivalent of `Nothing`?

CSharpFAQ — Fri, 12 Mar 2004 10:26:00 GMT

For reference types, the equivalent of VB's Nothing is C#'s null. For value types, it's the default value - 0, false, etc.

[Author: Jon Skeet]

Why doesn't C# have VB.NET's 'with' operator?

CSharpFAQ — Thu, 11 Mar 2004 10:02:00 GMT

Many people, including the C# language designers, believe that 'with' often harms readability, and is more of a curse than a blessing. It is clearer to declare a local variable with a meaningful name, and use that variable to perform multiple operations on a single object, than it is to have a block with a sort of implicit context.

For more information, see the Ask a C# Language Designer page.

[Author: Jon Skeet]

What are the advantages of C# over VB.NET and vice versa?

CSharpFAQ — Thu, 11 Mar 2004 09:59:00 GMT

The choice between C# and VB.NET is largely one of subjective preference. Some people like C#'s terse syntax, others like VB.NET's natural language, case-insensitive approach. Both have access to the same framework libraries. Both will perform largely equivalently (with a few small differences which are unlikely to affect most people, assuming VB.NET is used with Option Strict on). Learning the .NET framework itself is a much bigger issue than learning either of the languages, and it's perfectly possible to become fluent in both - so don't worry too much about which to plump for. There are, however, a few actual differences which may affect your decision:

VB.NET Advantages

Support for optional parameters - very handy for some COM interoperability
Support for late binding with Option Strict off - type safety at compile time goes out of the window, but legacy libraries which don't have strongly typed interfaces become easier to use.
Support for named indexers (aka properties with parameters).
Various legacy VB functions (provided in the Microsoft.VisualBasic namespace, and can be used by other languages with a reference to the Microsoft.VisualBasic.dll). Many of these can be harmful to performance if used unwisely, however, and many people believe they should be avoided for the most part.
The with construct: it's a matter of debate as to whether this is an advantage or not, but it's certainly a difference.
Simpler (in expression - perhaps more complicated in understanding) event handling, where a method can declare that it handles an event, rather than the handler having to be set up in code.
The ability to implement interfaces with methods of different names. (Arguably this makes it harder to find the implementation of an interface, however.)
Catch ... When ... clauses, which allow exceptions to be filtered based on runtime expressions rather than just by type.
The VB.NET part of Visual Studio .NET compiles your code in the background. While this is considered an advantage for small projects, people creating very large projects have found that the IDE slows down considerably as the project gets larger.

C# Advantages

XML documentation generated from source code comments. (This is coming in VB.NET with Whidbey (the code name for the next version of Visual Studio and .NET), and there are tools which will do it with existing VB.NET code already.)
Operator overloading - again, coming to VB.NET in Whidbey.
Language support for unsigned types (you can use them from VB.NET, but they aren't in the language itself). Again, support for these is coming to VB.NET in Whidbey.
The using statement, which makes unmanaged resource disposal simple.
Explicit interface implementation, where an interface which is already implemented in a base class can be reimplemented separately in a derived class. Arguably this makes the class harder to understand, in the same way that member hiding normally does.
Unsafe code. This allows pointer arithmetic etc, and can improve performance in some situations. However, it is not to be used lightly, as a lot of the normal safety of C# is lost (as the name implies). Note that unsafe code is still managed code, i.e. it is compiled to IL, JITted, and run within the CLR.

Despite the fact that the above list appears to favour VB.NET (if you don't mind waiting for Whidbey), many people prefer C#'s terse syntax enough to make them use C# instead.

[Author: Jon Skeet]

C# Frequently Asked Questions : C#/VB.NET Equivalents

How to keep a local variable in scope across a try and catch block?

Where can I get a full comparison between C# and VB.NET?

Is there an equivalent of MyClass?

What do I use instead of addressof?

How do I get the rightmost part of a string, as with the VB Right function?

What are the equivalents of Me and MyBase?

What's the equivalent of Nothing?

Why doesn't C# have VB.NET's 'with' operator?

What are the advantages of C# over VB.NET and vice versa?

VB.NET Advantages

C# Advantages

Is there an equivalent of `MyClass`?

What do I use instead of `addressof`?

How do I get the rightmost part of a string, as with the VB `Right` function?

What are the equivalents of `Me` and `MyBase`?

What's the equivalent of `Nothing`?