asp.net(c#)ref,out ,params的区别

复制代码 代码如下:

public partial class Form1 : Form
{
public static void UseParams(params int[] list)
{
string temp = "";
for (int i = 0; i < list.Length; i++)
temp = temp +" " +list[i].ToString();
MessageBox.Show(temp);
}
public static void UseParams2(params object[] list)
{
string temp = "";
for (int i = 0; i < list.Length; i++)
temp = temp + " " + list[i].ToString();
MessageBox.Show(temp);
}
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
UseParams(1, 2, 3);//看参数是3个
UseParams(1, 2); //看参数是2个，可变吧
UseParams2(1, 'a', "test");
int[] myarray = new int[3] { 10, 11, 12 };
UseParams(myarray); //看也可以是容器类，可变吧：）
}
}

复制代码 代码如下:

class MyClass
{
public void MyMethod(int i) {i = 10;}
public void MyMethod(out int i) {i = 10;}
}

复制代码 代码如下:

class MyClass
{
public void MyMethod(out int i) {i = 10;}
public void MyMethod(ref int i) {i = 10;}
}

复制代码 代码如下:

class MyClass
{
public void MyMethod(int i) {i = 10;}
public void MyMethod(ref int i) {i = 10;}
}

复制代码 代码如下:

class MyClass
{
public void MyMethod(out int i) {i = 10;}
public void MyMethod(ref int i) {i = 10;}
}

复制代码 代码如下:

public static string TestOut(out string i)
{
i = "out b";
return "return value";
}
public static void TestRef(ref string i)
{
//改变参数
i = "ref b";
}
public static void TestNoRef(string refi)
{
// 不用改变任何东西，这个太明显了
refi = "on c";
}
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string outi;//不需要初始化
MessageBox.Show(TestOut(out outi));//返回值
//输出"return value";
MessageBox.Show(outi);//调用后的out参数
//输出"out b";
string refi = "a"; // 必须初始化
TestRef(ref refi); // 调用参数
MessageBox.Show(refi);
//输出"ref b";
TestNoRef(refi);//不使用ref
MessageBox.Show(refi);
//输出"ref b";
}