Does one of these use more resources than the other?

Question

What is happening differently in the background for these two code blocks? Would one be considered "better" than the other?

My thought is that Example2 might be worse because it might have to wait for the garbage collector to dispose of the item, but I don't know enough about the garbage collector to know if that is true.

Example1:

ListItem item;
for (int i = 1; i <= 32; i++)
{
   item = new ListItem();
   //do some stuff
}

Example2:

for (int i = 1; i <= 32; i++)
{
   ListItem item = new ListItem();
   //do some stuff
}

Answer 1

I have copied your code into Visual Studio, compiled it, and then looked at the generated IL. This is the IL generated from Example 1:

.method private hidebysig static void  One() cil managed
{
  // Code size       30 (0x1e)
  .maxstack  2
  .locals init ([0] class WinTest.ListItem item,
           [1] int32 i,
           [2] bool CS$4$0000)
  IL_0000:  nop
  IL_0001:  ldc.i4.1
  IL_0002:  stloc.1
  IL_0003:  br.s       IL_0011
  IL_0005:  nop
  IL_0006:  newobj     instance void WinTest.ListItem::.ctor()
  IL_000b:  stloc.0
  IL_000c:  nop
  IL_000d:  ldloc.1
  IL_000e:  ldc.i4.1
  IL_000f:  add
  IL_0010:  stloc.1
  IL_0011:  ldloc.1
  IL_0012:  ldc.i4.s   32
  IL_0014:  cgt
  IL_0016:  ldc.i4.0
  IL_0017:  ceq
  IL_0019:  stloc.2
  IL_001a:  ldloc.2
  IL_001b:  brtrue.s   IL_0005
  IL_001d:  ret
} // end of method Program::One

And this is the IL generated from Example 2:

.method private hidebysig static void  Two() cil managed
{
  // Code size       30 (0x1e)
  .maxstack  2
  .locals init ([0] int32 i,
           [1] class WinTest.ListItem item,
           [2] bool CS$4$0000)
  IL_0000:  nop
  IL_0001:  ldc.i4.1
  IL_0002:  stloc.0
  IL_0003:  br.s       IL_0011
  IL_0005:  nop
  IL_0006:  newobj     instance void WinTest.ListItem::.ctor()
  IL_000b:  stloc.1
  IL_000c:  nop
  IL_000d:  ldloc.0
  IL_000e:  ldc.i4.1
  IL_000f:  add
  IL_0010:  stloc.0
  IL_0011:  ldloc.0
  IL_0012:  ldc.i4.s   32
  IL_0014:  cgt
  IL_0016:  ldc.i4.0
  IL_0017:  ceq
  IL_0019:  stloc.2
  IL_001a:  ldloc.2
  IL_001b:  brtrue.s   IL_0005
  IL_001d:  ret
} // end of method Program::Two

As far as I understand, they are identical except for the fact that locals are declared (and thus accessed) in reverse order. I don't expect that to have any impact on performance whatsoever.