C# vs VB.Net - implicit conversions

Question

This question is regarding implicit conversions in VB.Net and C#. The following C# code does not compile:

class Program
{
    static void Foo(string s)
    {
        Console.WriteLine(s);
    }

    static void Main(string[] args)
    {
        Foo(3); // Cannot convert from int to string
    }
}

The reason being that Foo expects a parameter of type string, but its given an int. A solution is to replace Foo(3) with Foo(3.ToString()). Fine.

Now, the same code authored in VB.Net:

Module Module1
    Sub Foo(s As String)
        Console.WriteLine(s)
    End Sub

    Sub Main()
        Foo(5)
    End Sub
End Module

This compiles and runs just fine!

Question: Why does VB.Net allow this and is there some fundamental difference between VB.Net and C# here?

Once you start "Strict On" in vb, it would be treated as error. — Ju-Hsien Lai, Jan 02 '16 at 00:32
@Plutonix That's correct. C# has no notion off "Option Strict", so there is a difference between these two .Net languages in this sense? — jensa, Jan 02 '16 at 00:32
VB Option Strict Off is mainly for backward compatibility (to people with VB6 background). C# has no such requirements, so there you go. — Ivan Stoev, Jan 02 '16 at 00:36
Possible duplicate of [Implicit casting in VB.NET](http://stackoverflow.com/questions/2619597/implicit-casting-in-vb-net) — T.S., Jan 07 '16 at 02:02

score 4 · Accepted Answer · answered Jan 02 '16 at 00:36

Programming languages make different trade-offs. VB.NET with Strict=Off is very lax. This is for historic compatibility reasons.

A few decades ago programming language designers thought that this behavior was helpful to beginners. Now we know that such lax behavior is terrible for program correctness and development speed.

JavaScript suffers from the same kind of problems, but worse.

Use strict semantics.

C# vs VB.Net - implicit conversions

1 Answers1