.net 实例化对象

定义TestClass，在调用的地方

TestClass a;

如果下面有引用

a.Property，VS会报错，而如果

TestClass a = null;

再次调用的话则不会报错。

TestClass a; DebugIL代码:

.method private hidebysig static void  Main(string[] args) cil managed
{
  .entrypoint
  // Code size       2 (0x2)
  .maxstack  0
  .locals init ([0] class ConsoleApplication1.TestClass a)
  IL_0000:  nop
  IL_0001:  ret
} // end of method Program::Main

TestClass a = null; DebugIL代码:

.method private hidebysig static void  Main(string[] args) cil managed
{
  .entrypoint
  // Code size       4 (0x4)
  .maxstack  1
  .locals init ([0] class ConsoleApplication1.TestClass a)
  IL_0000:  nop
  IL_0001:  ldnull
  IL_0002:  stloc.0
  IL_0003:  ret
} // end of method Program::Main

TestClass a; Release IL代码,VS会优化掉该语句

.method private hidebysig static void  Main(string[] args) cil managed
{
  .entrypoint
  // Code size       1 (0x1)
  .maxstack  8
  IL_0000:  ret
} // end of method Program::Main

TestClass a = null; Release IL代码，VS同样会优化掉该句

.method private hidebysig static void  Main(string[] args) cil managed
{
  .entrypoint
  // Code size       1 (0x1)
  .maxstack  8
  IL_0000:  ret
} // end of method Program::Main

先Mark，以后在具体研究区别