namespace FormConmunicate
{
/// <summary>
/// Form1 的摘要说明。
/// </summary>

public delegate string getText();

public class Form1 : System.Windows.Forms.Form
{
public System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.Button button1;
/// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.Container components = null;

public Form1()
{
//
// Windows 窗体设计器支持所必需的
//
InitializeComponent();

//
// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
//
}

/// <summary>
/// 清理所有正在使用的资源。
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

#region Windows Form Designer generated code
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.button1 = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(64, 40);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(88, 21);
this.textBox1.TabIndex = 0;
this.textBox1.Text = "textBox1";
//
// button1
//
this.button1.Location = new System.Drawing.Point(104, 168);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(96, 24);
this.button1.TabIndex = 1;
this.button1.Text = "button1";
//this.button1.Click += new System.EventHandler(this.button1_Click);
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
this.button1,
this.textBox1});

FormHandel.myFormHandel[0]=(int)this.Handle;

this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);

}
#endregion

/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Form1 f1=new Form1();
Form2 f2=new Form2();

f2.TextChange+=new TextChangeEventHander(f1.ontextchange);

f2.Show();

Application.Run(f1);
}

private void ontextchange(object sender,Form2EventArg e)
{
this.textBox1.Text=e.MyText ;

}
}

public class FormHandel
{
public static int[] myFormHandel={1,2};

}

}

//-----------------------------------------------
// form2.cs
//-----------------------------------------------
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;

namespace FormConmunicate
{
/// <summary>
/// Form2 的摘要说明。
/// </summary>
///

public delegate void TextChangeEventHander(object sender,Form2EventArg e);

public class Form2 : System.Windows.Forms.Form
{
public System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.Button button1;

public event TextChangeEventHander TextChange;

/// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.Container components = null;

public Form2()
{
//
// Windows 窗体设计器支持所必需的
//
InitializeComponent();

this.textBox1.Text=this.Handle.ToString();

//
// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
//
}

/// <summary>
/// 清理所有正在使用的资源。
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if(components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

#region Windows Form Designer generated code
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.button1 = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(168, 56);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(80, 21);
this.textBox1.TabIndex = 0;
this.textBox1.Text = "textBox1";
//
// button1
//
this.button1.Location = new System.Drawing.Point(168, 136);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(88, 24);
this.button1.TabIndex = 1;
this.button1.Text = "button1";
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// Form2
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
this.button1,
this.textBox1});

FormHandel.myFormHandel[1]=(int)this.Handle;
this.Name = "Form2";
this.Text = "Form2";
this.ResumeLayout(false);

}
#endregion

private void button1_Click(object sender, System.EventArgs e)
{

//引发事件，并传递数据
TextChange(this,new Form2EventArg(this.textBox1.Text));
}
}

//事件数据
public class Form2EventArg:System.EventArgs
{
private readonly string mytext ;

public Form2EventArg(string str)
{
mytext=str;
}

public string MyText
{
get
{
return mytext;
}

}
}

}

（出处：开发者俱乐部）