Amazing article on VB details and history

[KathleenDollard]

@AnthonyDGreen wrote an amazing article on VB.NET differences with C#.

I'd like to give this article, and the huge amount of Anthony's work it represents, as much visibility as possible and to pin it in this repo for reference.

Thank you Anthony!

[rskar-git]

A fantastic read, thank you! thank you! @AnthonyDGreen!
(Looking forward to 76+!)

I think though there is one erratum:

59. String concatenation is not the same...

The expression

 “1” + 1 

results in 2 (which is correctly shown under "Pet peeve" sub-section), not 11.0.

The expression

 1 + 1

results in Integer (2), not Double (2.0). Even in VBA, + was overloaded for integer vs. floating, as can be confirmed:

?vartype(1+1)
 2 
?vartype(1.0+1.0)
 5 
?vartype("1"+1)
 5 

Near as I can tell VB6/VBA got loosey-goosey about strings and numbers (and therefore VB.NET too) by way of influence from SQL (whether SQL Server, Oracle, or DB2) because VBA provides expression processing for MS Access (I guess). BASICs from Microsoft prior to VB did not do this. But in SQL Server e.g., SELECT '1' + 1 returns 2; and SELECT '1' + '1' returns 11.

Very nice and useful. Thank you @KathleenDollard and of cource @AnthonyDGreen
about 46, I tried this:

        Dim i As Object = 0
        Console.WriteLine(i Is Nothing) ' False
        Console.WriteLine(i = Nothing) ' True

It is really confusing!

[craigajohnson]

I believe regarding the above, i is a boxed integer and the default value of an integer is 0, so the null reference check will succeed (i is an object) and comparing the unboxed integer against the default value will also succeed.

Here is the IL generated confirming the boxing:

L_0000: nop
L_0001: ldc.i4.0
L_0002: box int32
L_0007: stloc.0
L_0008: ldloc.0
L_0009: ldnull
L_000a: ceq
L_000c: call void [mscorlib]System.Console::WriteLine(bool)
L_0011: nop
L_0012: ldloc.0
L_0013: ldnull
L_0014: ldc.i4.0
L_0015: call object [Microsoft.VisualBasic]Microsoft.VisualBasic.CompilerServices.Operators::CompareObjectEqual(object, object, bool)
L_001a: call object [mscorlib]System.Runtime.CompilerServices.RuntimeHelpers::GetObjectValue(object)
L_001f: call void [mscorlib]System.Console::WriteLine(object)
L_0024: nop
L_0025: ret