声明更接近其定义位置的变量？C#IL代码不一样

在C#中，我想知道我们是否应该将varbile clsoer声明到它的使用位置，是的，在同一个问题中有多个问题。但我还是有疑问

我尝试使用如下示例代码：

private void button1_Click(object sender, EventArgs e)
{
    for(int i= 0; i<=1000; i++)
    {
        int myVariable = 12;
        myVariable = i;
    }
}

/方法Form1的结尾：：按钮1\u单击

for循环外的变量：

.method private hidebysig instance void  button1_Click(object sender,
                                                       class [mscorlib]System.EventArgs e) cil managed
{
  // Code size       32 (0x20)
  .maxstack  2
  .locals init ([0] int32 i,
           [1] int32 myVariable,
           [2] bool CS$4$0000)
  IL_0000:  nop
  IL_0001:  ldc.i4.0
  IL_0002:  stloc.0
  IL_0003:  br.s       IL_0010
  IL_0005:  nop
  IL_0006:  ldc.i4.s   12
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  stloc.1
  IL_000b:  nop
  IL_000c:  ldloc.0
  IL_000d:  ldc.i4.1
  IL_000e:  add
  IL_000f:  stloc.0
  IL_0010:  ldloc.0
  IL_0011:  ldc.i4     0x3e8
  IL_0016:  cgt
  IL_0018:  ldc.i4.0
  IL_0019:  ceq
  IL_001b:  stloc.2
  IL_001c:  ldloc.2
  IL_001d:  brtrue.s   IL_0005
  IL_001f:  ret
} /

.method private hidebysig instance void  button1_Click(object sender,
                                                       class [mscorlib]System.EventArgs e) cil managed
{
  // Code size       32 (0x20)
  .maxstack  2
  .locals init ([0] int32 myVariable,
           [1] int32 i,
           [2] bool CS$4$0000)
  IL_0000:  nop
  IL_0001:  ldc.i4.s   12
  IL_0003:  stloc.0
  IL_0004:  ldc.i4.0
  IL_0005:  stloc.1
  IL_0006:  br.s       IL_0010
  IL_0008:  nop
  IL_0009:  ldloc.1
  IL_000a:  stloc.0
  IL_000b:  nop
  IL_000c:  ldloc.1
  IL_000d:  ldc.i4.1
  IL_000e:  add
  IL_000f:  stloc.1
  IL_0010:  ldloc.1
  IL_0011:  ldc.i4     0x3e8
  IL_0016:  cgt
  IL_0018:  ldc.i4.0
  IL_0019:  ceq
  IL_001b:  stloc.2
  IL_001c:  ldloc.2
  IL_001d:  brtrue.s   IL_0008
  IL_001f:  ret
} // end of method Form1::button1_Click

---

良好的实践完全取决于您的需求！如果您需要一个不同的变量，每次循环迭代，您都要在循环内部创建它，否则您应该将它放在外部。

确保您在启用优化的发布模式下编译。@MichaelLiu哇！那真是太不一样了！释放模式下的IL代码看起来完全不同，现在两个代码看起来完全相同。谢谢