通过c＃中的ref关键字调用类对象

Call class object by ref keyword in c#

本问题已经有最佳答案，请猛点这里访问。

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public class Test
{
public string Name;

public void CallFunctionByObjectRef(Test a)
{
a.Name ="BCD";
a = null;
}

public void CallFunctionByObjectRefTORef(ref Test a)
{
a.Name ="BCD";
a = null;
}
}

class Program
{
static void Main(string[] args)
{

Test test = new Test();
test.Name ="ABC";
test.CallFunctionByObjectRef(test);

Test test1 = new Test();
test1.Name ="ABC";
test1.CallFunctionByObjectRefTORef(ref test1);

Console.WriteLine(test.Name);
Console.WriteLine(test1.Name);
Console.Read();
}
}

在上面调用了两个函数(使用ref关键字，pass-by-object)。我从他们那里得到了不同的产出。但是类对象在默认情况下通过引用传递，这就是为什么我得到不同的输出。

相关讨论

在您的例子中，对类对象的引用是按值传递的。

给定值或引用类型的变量a和方法，接受a作为值或引用：

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class A {}
// or
struct A {}

var a = new A();

Foo(ref a);
// or
Foo(a);

你可以：

按值传递引用类型：可以更改变量引用的对象，不能更改变量本身。
通过引用传递引用类型：可以更改变量引用的对象，也可以更改变量本身。
按值传递值类型：不能更改变量引用的对象，也不能更改变量本身。
按引用传递值类型：可以更改变量引用的对象，不能更改变量本身。

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/* Here you are passing pointer to the variable. For example variable test has got memory address
* 0X200001.
* When you pass test, you are saying that there are two variables that points to 0X200001 (one in main and another in CallFunctionByObjectRef i.e. variable a)
* Thus when you are changing the value for a variable to null, you are changing the direction to link with null memory location.
*
* It is called reference.
* When you came back to Main, test variable is still pointing to the memory 0X200001
*/
Test test = new Test();
test.Name ="ABC";

test.CallFunctionByObjectRef(test);

/*
* In this case you are saying that create a variable test1 that gives a memory as: 0X200002
* Then you are passing a pointer to pointer i.e. you are sending an actual test1 variable.
* so whatever you will change here will get impacted in Main.
*/
Test test1 = new Test();
test1.Name ="ABC";

test1.CallFunctionByObjectRefTORef(ref test1);

Console.WriteLine(test.Name);
Console.WriteLine(test1.Name);
Console.Read();

如果你想了解更多，那么你需要从C/C++指针编程中得到一个想法，并搜索"指针的引用"。