const string vs static readonly string

namespace BugQiang.Al {
    public class ClassA1 {
        public static readonly string STATIC_READONLY_STRING = "STATIC_READONLY_STRING";
        public const string CONST_STRING = "CONST_STRING";
    }
}

using System;
using BugQiang.Al;

namespace BugQiang.B1 {
    public class ClassB1 {
        public static void ShowClassA1() {
            Console.WriteLine("ClassA1.CONST_STRING = {0}
ClassA1.STATIC_READONLY_STRING = {1}",
                ClassA1.CONST_STRING,
                ClassA1.STATIC_READONLY_STRING);
        }
    }

    class Program {
        static void Main() {
            ClassB1.ShowClassA1();
        }
    }
}

编译并运行：
C:UsersdeDesktopao>csc /t:library /nologo ClassA1.cs

C:UsersdeDesktopao>csc /r:ClassA1.dll /nologo ClassB1.cs

C:UsersdeDesktopao>ClassB1
ClassA1.CONST_STRING = CONST_STRING
ClassA1.STATIC_READONLY_STRING = STATIC_READONLY_STRING

C:UsersdeDesktopao>

重新编辑ClassA1.cs

namespace BugQiang.Al {
    public class ClassA1 {
        public static readonly string STATIC_READONLY_STRING = "REBUILD_STATIC_READONLY_STRING";
        public const string CONST_STRING = "REBUILD_CONST_STRING";
    }
}

重新编译ClassA1.cs,并运行ClassB1.exe:
C:UsersdeDesktopao>csc /t:library /nologo ClassA1.cs

C:UsersdeDesktopao>ClassB1
ClassA1.CONST_STRING = CONST_STRING
ClassA1.STATIC_READONLY_STRING = REBUILD_STATIC_READONLY_STRING

C:UsersdeDesktopao>

？？？？

反编译打开ClassB1.exe

C:UsersdeDesktopao>ildasm

C:UsersdeDesktopao>

打开ClassB1.exe后，view/metainfo/show! (Ctrl + M)

在metainfo的最底部有这么一节:

User Strings
-------------------------------------------------------
70000001 : (64) L"ClassA1.CONST_STRING = {0} ClassA1.STATIC_READONLY_STRING = {1}"
70000084 : (12) L"CONST_STRING"

以及ClassB1.ShowClassA1对应的IL代码

.method public hidebysig static void  ShowClassA1() cil managed
{
  // Code size       23 (0x17)
  .maxstack  8
  IL_0000:  nop
  IL_0001:  ldstr      "ClassA1.CONST_STRING = {0} ClassA1.STATIC_READONL"
  + "Y_STRING = {1}"
  IL_0006:  ldstr      "CONST_STRING"
  IL_000b:  ldsfld     string [ClassA1]BugQiang.Al.ClassA1::STATIC_READONLY_STRING
  IL_0010:  call       void [mscorlib]System.Console::WriteLine(string,
                                                                object,
                                                                object)
  IL_0015:  nop
  IL_0016:  ret
} // end of method ClassB1::ShowClassA1

结束语:.NET字符串驻留机制