如下代码：
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
var (a, b, c) = ("a","b","c");
myRef(ref a,out b,c);
Console.WriteLine(a+b+c);
Console.ReadKey();
}
static void myRef(ref string a, out string b, string c)
{
a = "aaa";
b = "bbb";
c = "ccc";
}
查看IL:
1 .method private hidebysig static 2 void Main ( 3 string[] args 4 ) cil managed 5 { 6 // Method begins at RVA 0x2050 7 // Code size 62 (0x3e) 8 .maxstack 3 9 .entrypoint 10 .locals init ( 11 [0] string a, 12 [1] string b, 13 [2] string c 14 ) 15 16 // (no C# code) 17 IL_0000: nop 18 // Console.WriteLine("Hello World!"); 19 IL_0001: ldstr "Hello World!" 20 IL_0006: call void [System.Console]System.Console::WriteLine(string) 21 // (no C# code) 22 IL_000b: nop 23 // string a = "a"; 24 IL_000c: ldstr "a" 25 IL_0011: stloc.0 26 // string b = "b"; 27 IL_0012: ldstr "b" 28 IL_0017: stloc.1 29 // string text = "c"; 30 IL_0018: ldstr "c" 31 IL_001d: stloc.2 32 // myRef(ref a, out b, text); 33 IL_001e: ldloca.s 0 34 IL_0020: ldloca.s 1 35 IL_0022: ldloc.2 36 IL_0023: call void ConsoleApp1.Program::myRef(string&, string&, string) 37 // (no C# code) 38 IL_0028: nop 39 // Console.WriteLine(a + b + text); 40 IL_0029: ldloc.0 41 IL_002a: ldloc.1 42 IL_002b: ldloc.2 43 IL_002c: call string [System.Runtime]System.String::Concat(string, string, string) 44 IL_0031: call void [System.Console]System.Console::WriteLine(string) 45 // (no C# code) 46 IL_0036: nop 47 // Console.ReadKey(); 48 IL_0037: call valuetype [System.Console]System.ConsoleKeyInfo [System.Console]System.Console::ReadKey() 49 IL_003c: pop 50 // } 51 IL_003d: ret 52 } // end of method Program::Main
可以看到，这里ref 和Out 用到了指针。
最后将对象引用（类型 O）值存储在给定地址 ，Out 在方法上 多了一个 [out]