Example of communication between forms of the C program using callback events

Form2:

// define 1 A need to string The delegate of the type parameter          
publicdelegate void MyDelegate(string text);         
public partial class Form2 :Form1     
    {         
       // The event that defines the delegate      
        public event MyDelegate MyEvent;     
        public Form2(string text)     
        {      
            InitializeComponent();     
            this.textBox1.Text = text;     
       }     
       private void btnChange_Click(object sender, EventArgs e)                   
       {     
           // Triggers an event and sends the modified text back      
           MyEvent(this.textBox1.Text);     
           this.Close();     
        }     
   }

Form1:

public partial class Form1 :Form     
    {     
        public int index = 0;     
        public string text = null;     
        public Form1()     
        {     
            InitializeComponent();     
        }     

        private void listBox1_SelectedIndexChanged(object sender, EventArgse)     
        {     
            if (this.listBox1.SelectedItem != null)     
            {     
                text = this.listBox1.SelectedItem.ToString();     
                index = this.listBox1.SelectedIndex;     
                Form2 form2 = new Form2(text);     

               // registered form2_MyEvent methods MyEvent The event      
                form2.MyEvent += new MyDelegate(form2_MyEvent);     
                form2.Show();     
            }     
        }     

       // To deal with      

        void form2_MyEvent(string text)     
        {     
            this.listBox1.Items.RemoveAt(index);     
            this.listBox1.Items.Insert(index, text);     
       }     
   }