List<int>ListInt = new List<int>();
int item = 100;
ListInt.Add(item);

.locals init ([0] class [mscorlib]System.Collections.Generic.List`1<int32> ListInt,
           [1] int32 item)
  IL_0000:  nop
  IL_0001:  newobj     instance void class [mscorlib]System.Collections.Generic.List`1<int32>::.ctor()
  IL_0006:  stloc.0
  IL_0007:  ldc.i4.s   101
  IL_0009:  stloc.1
  IL_000a:  ldloc.0
  IL_000b:  ldloc.1
  IL_000c:  callvirt   instance void class [mscorlib]System.Collections.Generic.List`1<int32>::Add(!0)
  IL_0011:  nop
  IL_0012:  ret