C#中使用API来实现BEEP

using  System;
using  System.Drawing;
using  System.Collections;
using  System.ComponentModel;
using  System.Windows.Forms;
using  System.Data;
using  System.Runtime.InteropServices;   // 之前必须要添加此引用!
namespace  BEEP
... {

    public class Form1 : System.Windows.Forms.Form
    ...{
        private System.ComponentModel.Container components = null;
        public Form1()...{LoadForm();}

      /******************************关键在此, 不要改.************************/
        [DllImport("kernel32.dll")]
        private static extern bool Beep(int freq, int dur);
        public const int SND_FILENAME = 0x00020000;
        private System.Windows.Forms.TextBox textBox1;
        private System.Windows.Forms.TextBox textBox2;
        private System.Windows.Forms.Button button1;
        public const int SND_ASYNC = 0x0001;
        [DllImport("winmm.dll")]
        public static extern bool PlaySound(string pszSound,int hmod,int fdwSound);

/**************************************************************************/

        protected override void Dispose( bool disposing )
        ...{
            if( disposing )
            ...{
                if (components != null) 
                ...{
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }




        private void LoadForm()
        ...{
                    //..............窗体控件初始化,省略............//
        }





        [STAThread]
        static void Main() 
        ...{
            Application.Run(new Form1());
        }



        private void button1_Click(object sender, System.EventArgs e)
        ...{
            try
            ...{
                Beep(int.Parse(textBox1.Text),int.Parse(textBox2.Text));

     /*                 ^^^^^^^^^^^^^^^^^      ^^^^^^^^^^^^^^     */

     /*                                          数值1                            数值2                       */
            }
            catch...{
                      
            }
        }
        
    }
}