Passing Data Between Forms

• Download demo project - 109 Kb

Passing Data Between Forms 

Introduction

Some of you would have faced a scenario where you wanted to pass data from one form to another in WinForms. Honestly, I too had a similar problem (that’s why I am writing this article!).           

There are so many methods (How many? I don’t know) to pass data between forms in windows application. In this article let me take four important (easiest) ways of accomplishing this.

1. Using constructor
2. Using objects
3. Using properties
4. Using delegates

Let us see all the above methods in detail in the following sections.

            For a data to be passed between forms using any of the above methods, we need two forms and some controls. Let us start by following the below steps.

Step 1: Create new project and select windows application. This will create a default form as “Form1”. We can use this form for sending data.

Step 2: Add a textbox and a button to the form.

Step 3: Add another windows form for receiving the data and to display it. Right click the project and select Add->Add Windows Form. Enter a name or use the default name “Form2.cs” and click ok button.

Step 4: Add a label to the second form to display the text from form1

The Constructor Approach

            This could be the easiest method of all. A method is invoked whenever you instantiate an object. This method is called a constructor. Code a constructor for form2 class with one string parameter. In the constructor assign the text to the label’s text property. Instantiate form2 class in form1’s button click event handler using the constructor with one string parameter and pass the textbox’s text to the constructor.

Follow the below steps.

Step 1: Code a constructor for form2 class as below

public Form2(string strTextBox)
{
  InitializeComponent(); 
  label1.Text=strTextBox;
}

private void button1_Click(object sender, System.EventArgs e)
{
    Form2 frm=new Form2(textBox1.Text);
    frm.Show();
}

public class Form1 : System.Windows.Forms.Form

{  

 public System.Windows.Forms.TextBox textBox1;

private void btnSend_Click(object sender, System.EventArgs e)
{
    Form2 frm= new Form2();
    frm.frm1=this;
    frm.Show();
}

public class Form2 : System.Windows.Forms.Form
{
     private System.Windows.Forms.Label label1;
     public Form1 frm1;

private void Form2_Load(object sender, System.EventArgs e)
{
    label1.Text=((Form1)frm1).textBox1.Text;
}

public string _textBox1
{
    get{return textBox1.Text;}
}

public string _textBox
{
   set{label1.Text=value;}
}

private void button1_Click(object sender, System.EventArgs e)
{
     Form2 frm=new Form2();
     frm._textBox=_textBox1;
     frm.Show();
}

public delegate void delPassData(TextBox text);

private void btnSend_Click(object sender, System.EventArgs e)
{
    Form2 frm= new Form2();
    delPassData del=new delPassData(frm.funData);
    del(this.textBox1);
    frm.Show();
}

public void funData(TextBox txtForm1)
{
    label1.Text = txtForm1.Text;
}