String concatenation: using += vs. &=

Question

Possible Duplicate:
The difference between + and & for joining strings in VB.Net

In VB.NET you can use either += or &= to concatenante a string (ignoring using a StringBuilder for this question -- this is directed at a very simple concatenation).

I'm curious to know if and what the differences are of using one or the other in VB.NET.

Answer 1

Several threads have addressed this:

http://stackoverflow.com/questions/734600/the-difference-between-and-for-joining-strings-in-vb-net

http://stackoverflow.com/questions/3006153/vb-net-ampersand-vs-plus-for-concatenating-string

Answer 2

None.

As you can see below. These two lines of code compiles exactly to the same IL code:

Module Module1

Sub Main()
    Dim s1 As String = "s1"
    Dim s2 As String = "s2"
    s2 += s1
    s1 &= s2
End Sub

End Module

Compiles to (note System.String::Concat):

.method public static void  Main() cil managed
{
.entrypoint
.custom instance void [mscorlib]System.STAThreadAttribute::.ctor() = ( 01 00 00 00 ) 
// Code size       31 (0x1f)
.maxstack  2
.locals init ([0] string s1,
       [1] string s2)
IL_0000:  nop
IL_0001:  ldstr      "s1"
IL_0006:  stloc.0
IL_0007:  ldstr      "s2"
IL_000c:  stloc.1
IL_000d:  ldloc.1
IL_000e:  ldloc.0
IL_000f:  call       string [mscorlib]System.String::Concat(string,
                                                          string)
IL_0014:  stloc.1
IL_0015:  ldloc.0
IL_0016:  ldloc.1
IL_0017:  call       string [mscorlib]System.String::Concat(string,
                                                          string)
IL_001c:  stloc.0
IL_001d:  nop
IL_001e:  ret
} // end of method Module1::Main