C#窗体间传值，非父窗体与子窗体

在C#中，窗体间传值是一个常见的需求，尤其在非父子关系的窗体之间传值。下面介绍几种常用的方法：

### 1. 使用公共变量
可以在一个公共类中定义静态变量，然后在不同的窗体中访问这些变量。

// 公共类
public static class CommonData
{
    public static string Data { get; set; }
}

// 窗体1
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        CommonData.Data = "Hello from Form1";
        Form2 form2 = new Form2();
        form2.Show();
    }
}

// 窗体2
public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
    }

    private void Form2_Load(object sender, EventArgs e)
    {
        label1.Text = CommonData.Data;
    }
}

### 2. 使用构造函数
在创建子窗体时，通过构造函数传递数据。

// 窗体1
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        string data = "Hello from Form1";
        Form2 form2 = new Form2(data);
        form2.Show();
    }
}

// 窗体2
public partial class Form2 : Form
{
    private string receivedData;

    public Form2(string data)
    {
        InitializeComponent();
        receivedData = data;
    }

    private void Form2_Load(object sender, EventArgs e)
    {
        label1.Text = receivedData;
    }
}

### 3. 使用事件
通过事件机制传递数据。

// 公共事件参数类
public class DataEventArgs : EventArgs
{
    public string Data { get; set; }
}

// 窗体1
public partial class Form1 : Form
{
    public event EventHandler<DataEventArgs> DataSent;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        DataEventArgs args = new DataEventArgs { Data = "Hello from Form1" };
        DataSent?.Invoke(this, args);
    }
}

// 窗体2
public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
    }

    private void Form2_Load(object sender, EventArgs e)
    {
        Form1 form1 = new Form1();
        form1.DataSent += Form1_DataSent;
        form1.Show();
    }

    private void Form1_DataSent(object sender, DataEventArgs e)
    {
        label1.Text = e.Data;
    }
}

### 4. 使用委托
通过委托传递数据。

// 窗体1
public partial class Form1 : Form
{
    public delegate void SendDataDelegate(string data);
    public event SendDataDelegate SendData;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        SendData?.Invoke("Hello from Form1");
    }
}

// 窗体2
public partial class Form2 : Form
{
    private string receivedData;

    public Form2()
    {
        InitializeComponent();
    }

    private void Form2_Load(object sender, EventArgs e)
    {
        Form1 form1 = new Form1();
        form1.SendData += Form1_SendData;
        form1.Show();
    }

    private void Form1_SendData(string data)
    {
        label1.Text = data;
    }
}