C#通过不安全代码看内存加载

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&＃xff08;注&＃xff1a;本篇用点长&＃xff0c;有点绕&＃xff0c;耐心浏览&＃xff09;

C#中类型分为值类型和引用类型&＃xff0c;值类型存储在堆栈中&＃xff0c;是栈结构&＃xff0c;先进后出&＃xff0c;引用类型存储在托管堆中。接下来用不安全代码的地址&＃xff0c;来看一下值类型和引用类型的存储。

项目文件

C#中使用不安全代码需要在项目文件中添加AllowUnsafeBlocks配置。



Exe
net7.0
enable
enable
true
  


所有的测试案例都是定义两个特定类型的变量&＃xff0c;然后查看它的内存地址&＃xff0c;然后进行调用一个方法进行相加运算&＃xff0c;然后分别在方法内输出变量和结查内存地址&＃xff0c;最后返回主方法后变量的内存地址。

值类型&＃xff1a;

static void TestDouble()
var v1 &＃61; 1.00001d;
var v2 &＃61; 2.00002d;
Console.WriteLine("TestDouble v1 " &＃43; (long)&v1);
Console.WriteLine("TestDouble v2 " &＃43; (long)&v2);
Console.WriteLine("TestDouble v2-v1 " &＃43; ((long)&v2 - (long)&v1));
var v3 &＃61; Add(v1, v2);
Console.WriteLine("TestDouble v3 " &＃43; (long)&v3);
Console.WriteLine("TestDouble v3-v2 " &＃43; ((long)&v3 - (long)&v2));
Console.WriteLine("TestDouble v3-v1 " &＃43; ((long)&v3 - (long)&v1));
static double Add(double v1, double v2)
Console.WriteLine("Add v1 " &＃43; (long)&v1);
Console.WriteLine("Add v2 " &＃43; (long)&v2);
Console.WriteLine("Add v2-v1 " &＃43; ((long)&v2 - (long)&v1));
var v3 &＃61; v1 &＃43; v2;
Console.WriteLine("Add v3 " &＃43; (long)&v3);
Console.WriteLine("Add v3-v2 " &＃43; ((long)&v3 - (long)&v2));
Console.WriteLine("Add v3-v1 " &＃43; ((long)&v3 - (long)&v1));
return v3;


v1的所在内存地址大于v2&＃xff0c;最后运算完的v3是最小的&＃xff0c;我们可以想象&＃xff0c;v1放在栈的最后面&＃xff0c;地址最大&＃xff0c;然后放v2&＃xff0c;最后放v3。回收时的顺序是反回来的。那么Add方法里&＃xff0c;v2地址最大&＃xff0c;但比TestDouble都要小&＃xff0c;说明进栈要晚一些&＃xff0c;接下来是v1进栈&＃xff0c;最后是v3进栈&＃xff0c;不过TestDouble里的每个变量都相差8&＃xff0c;但方法里的就不是了&＃xff0c;这是因为方法参数&＃xff0c;返回值等信息&＃xff0c;还要占一些内存空间。还有TestDouble的v3为什么能和v2相差8&＃xff1f;不是有Add方法吗&＃xff1f;原因是Add调用完后都出栈了&＃xff0c;所以TestDouble的v3和v2是相邻的。

自定义结构体&＃xff1a;

struct TestStruct
public TestStruct()

i &＃61; 100;

public long i;
static void TestTestStruct()
var v1 &＃61; new TestStruct();
Console.WriteLine("TestStruct原v1对象地址&＃61; " &＃43; (long)&v1);
var v2 &＃61; new TestStruct();
Console.WriteLine("TestStruct原v2对象地址&＃61; " &＃43; (long)&v2);
Console.WriteLine("TestStruct v2-v1 " &＃43; ((long)&v2 - (long)&v1));
    var v3 &＃61; Add(v1, v2);
Console.WriteLine("TestStruct原v3对象地址&＃61; " &＃43; (long)&v3);
Console.WriteLine("TestStruct v3-v2 " &＃43; ((long)&v3 - (long)&v2));
static TestStruct Add(TestStruct v1, TestStruct v2)
Console.WriteLine("Add TestStruct v1对象地址&＃61; " &＃43; (long)&v1);
Console.WriteLine("Add TestStruct v2对象地址&＃61; " &＃43; (long)&v2);
Console.WriteLine("Add TestStruct v2-v1 " &＃43; ((long)&v2 - (long)&v1));
var v3 &＃61; new TestStruct();
v3.i &＃61; v1.i &＃43; v2.i;
Console.WriteLine("Add TestStruct v3对象地址" &＃43; (long)&v3);
Console.WriteLine("Add TestStruct v3-v2 " &＃43; ((long)&v3 - (long)&v2));
return v3;


自定义struct与double类似&＃xff0c;本质上double也是用struct定义的。

引用类型string

static void TestString()
long ad1, ad2, ad3;
var v1 &＃61; "aaaa";
var v2 &＃61; "bbbb";
fixed (char* p &＃61; v1)

ad1 &＃61; (long)p;
Console.WriteLine("TestString v1字符串地址&＃61; " &＃43; (long)p);

fixed (char* p &＃61; v2)

ad2 &＃61; (long)p;
Console.WriteLine("TestString v2字符串地址&＃61; " &＃43; (long)p);

Console.WriteLine("TestString v2-v1 " &＃43; (ad2 - ad1));
var v3 &＃61; Add(v1, v2);
fixed (char* p &＃61; v3)

ad3 &＃61; (long)p;
Console.WriteLine("TestString v3字符串地址&＃61; " &＃43; (long)p);

Console.WriteLine("TestString v3-v2 " &＃43; (ad3 - ad2));
static string Add(string v1, string v2)
long ad1, ad2, ad3;
fixed (char* p &＃61; v1)

ad1 &＃61; (long)p;
Console.WriteLine("Add中v1字符串地址&＃61; " &＃43; (long)p);

fixed (char* p &＃61; v2)

ad2 &＃61; (long)p;
Console.WriteLine("Add中v2字符串地址&＃61; " &＃43; (long)p);

Console.WriteLine("Add中 v2-v1 " &＃43; (ad2 - ad1));
var v3 &＃61; v1 &＃43; v2;
fixed (char* p &＃61; v3)

ad3 &＃61; (long)p;
Console.WriteLine("Add中v3字符串地址&＃61; " &＃43; (long)p);

Console.WriteLine("Add中 v3-v2 " &＃43; (ad3 - ad2));
Console.WriteLine("Add中 v3-v1 " &＃43; (ad3 - ad1));
return v3;
static void TestString2()
var v1 &＃61; "aaaa";
var v2 &＃61; "bbbb";
var h1 &＃61; GCHandle.Alloc(v1, GCHandleType.Pinned);
Console.WriteLine("TestString2 v1对象地址&＃61; " &＃43; (long)h1.AddrOfPinnedObject());
var h2 &＃61; GCHandle.Alloc(v2, GCHandleType.Pinned);
Console.WriteLine("TestString2 v2对象地址&＃61; " &＃43; (long)h2.AddrOfPinnedObject());
Console.WriteLine("TestString2 v2-v1 " &＃43; ((long)h2.AddrOfPinnedObject() - (long)h1.AddrOfPinnedObject()));
var v3 &＃61; Add2(v1, v2);
var h3 &＃61; GCHandle.Alloc(v3, GCHandleType.Pinned);
Console.WriteLine("TestString2 v3对象地址&＃61; " &＃43; (long)h3.AddrOfPinnedObject());
Console.WriteLine("TestString2 v3-v2 " &＃43; ((long)h3.AddrOfPinnedObject() - (long)h2.AddrOfPinnedObject()));
static string Add2(string v1, string v2)
var h1 &＃61; GCHandle.Alloc(v1, GCHandleType.Pinned);
Console.WriteLine("Add2中的v1对象地址&＃61; " &＃43; (long)h1.AddrOfPinnedObject());
var h2 &＃61; GCHandle.Alloc(v2, GCHandleType.Pinned);
Console.WriteLine("Add2中的v2对象地址&＃61; " &＃43; (long)h2.AddrOfPinnedObject());
Console.WriteLine("Add2 v2-v1 " &＃43; ((long)h2.AddrOfPinnedObject() - (long)h1.AddrOfPinnedObject()));
var v3 &＃61; v1 &＃43; v2;
var h3 &＃61; GCHandle.Alloc(v3, GCHandleType.Pinned);
Console.WriteLine("Add2中的v3对象地址&＃61; " &＃43; (long)h3.AddrOfPinnedObject());
Console.WriteLine("Add2 v3-v2 " &＃43; ((long)h3.AddrOfPinnedObject() - (long)h2.AddrOfPinnedObject()));
Console.WriteLine("Add2 v3-v1 " &＃43; ((long)h3.AddrOfPinnedObject() - (long)h1.AddrOfPinnedObject()));
return v3;


字符串是引用类型&＃xff0c;v1比v2内存地址小&＃xff0c;进入Add后&＃xff0c;v1和v2与传入的地址相同&＃xff0c;因为是引用类型&＃xff0c;Add方法里的v3接着往大走&＃xff0c;并且与返回的v3是一个地址&＃xff0c;这些没有问题。

string用了两种方法&＃xff0c;发现两个方式v1都是aaaa,v2都是bbbb&＃xff0c;因为字符串有留用性&＃xff0c;所以两个方法的v1和v2是一样的&＃xff1b;但两种方式调用了Add后&＃xff0c;在Add里的v3都是aaaabbbb&＃xff0c;都是拼接&＃xff0c;但拼出来的字符串的地址不相同&＃xff0c;所以这块没有留用。

自定class类型

class TestClass
public int i &＃61; 100;
static void TestTestClass()
var v1 &＃61; new TestClass();
var h1 &＃61; GCHandle.Alloc(v1, GCHandleType.Pinned);
Console.WriteLine("TestTestClass v1对象地址&＃61; " &＃43; (long)h1.AddrOfPinnedObject());
var v2 &＃61; new TestClass();
var h2 &＃61; GCHandle.Alloc(v2, GCHandleType.Pinned);
Console.WriteLine("TestTestClass v2对象地址&＃61; " &＃43; (long)h2.AddrOfPinnedObject());
    Console.WriteLine("TestTestClass v2-v1 " &＃43; ((long)h2.AddrOfPinnedObject() - (long)h1.AddrOfPinnedObject()));
    var v3 &＃61; Add(v1, v2);
var h3 &＃61; GCHandle.Alloc(v3, GCHandleType.Pinned);
Console.WriteLine("TestTestClass 3对象地址&＃61; " &＃43; (long)h3.AddrOfPinnedObject());
    Console.WriteLine("TestTestClass v3-v2 " &＃43; ((long)h3.AddrOfPinnedObject() - (long)h2.AddrOfPinnedObject()));
static TestClass Add(TestClass v1, TestClass v2)
var h1 &＃61; GCHandle.Alloc(v1, GCHandleType.Pinned);
Console.WriteLine("Add中的v1对象地址&＃61; " &＃43; (long)h1.AddrOfPinnedObject());
var h2 &＃61; GCHandle.Alloc(v2, GCHandleType.Pinned);
Console.WriteLine("Add中的v2对象地址&＃61; " &＃43; (long)h2.AddrOfPinnedObject());
    Console.WriteLine("Add中 v2-v1 " &＃43; ((long)h2.AddrOfPinnedObject() - (long)h1.AddrOfPinnedObject()));
    var v3 &＃61; new TestClass();
v3.i &＃61; v1.i &＃43; v2.i;
var h3 &＃61; GCHandle.Alloc(v3, GCHandleType.Pinned);
Console.WriteLine("Add中的v3对象地址&＃61; " &＃43; (long)h3.AddrOfPinnedObject());
Console.WriteLine("Add中 v3-v2 " &＃43; ((long)h3.AddrOfPinnedObject() - (long)h2.AddrOfPinnedObject()));
Console.WriteLine("Add中 v3-v1 " &＃43; ((long)h3.AddrOfPinnedObject() - (long)h1.AddrOfPinnedObject()));
return v3;


自定义class&＃xff0c;每次都是新地址&＃xff0c;没有留用性&＃xff0c;并且地址都是在增加。

当然引用类型的地址不是一成不变的&＃xff0c;因为有垃圾回放&＃xff0c;重新整理的过程&＃xff0c;本例用用Pinned的方式固定&＃xff0c;不过代码量少的情况也不一定能触发回收。