passing data between 3 windows forms in visual studio using C#

Question

I have a windows application which has 3 forms : Form1,2,3. I want to send text of a textbox from form2 to form1 and then that same text from form1 to form3, that is,

Text from FORM2-->FORM1-->FORM3

Form 1, has 2 buttons , openform2, openform3.
Form2 has a textbox form2_textbox, & a button send_to_form1_button
Form3 has a textbox received_from_form1_textbox

Now,

on clicking button openform2 on form1, Form2 opens,
a string is entered in textbox form2_textbox of Form2,
when button form2_button of this form is clicked, then I want Form1 to receive this string value & stores it in a string receivefromform2,
and then displays this string value on to form3_textbox of Form3.

public partial class Form1 : Form
{
    string receivefromForm2a;

    public Form1()
    { InitializeComponent(); }

    public void Method_Receive_From_Form2(string receivefromForm2)
    {
        receivefromForm2a = receivefromForm2;
        Form3 f3 = new Form3(receivefromForm2a);
    }

    private void openform3_Click(object sender, EventArgs e)
        {
            Form3 f3 = new Form3();**----this line gives error:No overload for method Form3 takes 0 arguments**

            f3.Show();
        }

    private void OPENFORM2_Click(object sender, EventArgs e)
    {
        Form2 f2 = new Form2();
        f2.Show();
    }
}

public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
        string loginname = form2_textbox.Text;
    }

    //SENDING VALUE OF TEXTBOX ON FORM2 TO FORM1.

    private void send_to_form1_button_Click(object sender, EventArgs e)
    {
        Form1 f1 = new Form1();
        f1.Method_Receive_From_Form2(form2_textbox.Text);
    }
}

public partial class Form3 : Form
{
    public Form3(string receive_from_Form1)
    {
        InitializeComponent();
        received_from_form1_textbox.Text = receive_from_Form1;
    }
}

This error occurs because in form2 I have given argument for form1 during object creation. So what should I do? Is there any other way to do this or how do I remove this error?

When I include the f3.Show() in the method Method_Receive_From_Form2 then there is no error. but this makes the form3 load automatically without any button click. But I want form3 to open by clicking the button on form1. And then the value to be shown in the textbox.

Tony Abrams · Accepted Answer · 2011-02-21 15:16:02Z

I would recommend a change from using constructors to using properties. This will keep things properly 'contained' and it's pretty simple.

EX:

public partial class Form3 : Form
{
   public String form1Text {get; set;}

   public Form3()
   {
       InitializeComponent();
   }
}

public partial class Form2 : Form
{
   public Form2()
   {
       InitializeComponent();
       string loginname = form2_textbox.Text;
   }

   public String form2Text {get; set;}

   private void send_to_form1_button_Click(object sender, EventArgs e)
   {

       form2Text = form2_textbox.Text;
       this.DialogResult = DialogResult.Ok;
       this.Close();
   }
}

Then in form 1:

public partial class Form1 : Form
{
   string receivefromForm2a;

   public Form1()
   { InitializeComponent(); }       

    private void openform3_Click(object sender, EventArgs e)
    {
        Form3 f3 = new Form3();
        f3.form1Text = receivefromForm2a;
        f3.Show();
    }

private void OPENFORM2_Click(object sender, EventArgs e)
{
    Form2 f2 = new Form2();
    if(f2.ShowDialog() == DialogResult.Ok)
    {
      receivefromForm2a = f2.form2Text; //New Property on Form2.
    }
}
}

Sergey Vedernikov · Accepted Answer · 2011-02-18 11:00:37Z

1

create nonparametrized constructor for form3 like in form2:

public Form3() { InitializeComponent(); }

This usually to create abstract methods in forms and/or delegates for updating textboxes and sharing data between forms. Or create some data holder.

answered Feb 18, 2011 at 11:00

Sergey Vedernikov

7,7542 gold badges27 silver badges27 bronze badges

Comments

Novice · Accepted Answer · 2011-02-18 12:52:25Z

1

Create a Constructor which has an argument of type string in Form3.cs.

public Form3()
{
   InitializeComponent();
}
public Form3(string text):this()
{
   this.txtName.text=text;
}

answered Feb 18, 2011 at 12:52

Novice

2,4973 gold badges27 silver badges33 bronze badges

1 Comment

sqlchild Over a year ago

please explain this, and tell me that which code should i remove from my existing code? its not working sir?

Shekhar_Pro · Accepted Answer · 2011-02-19 03:29:48Z

1

That error is thrown because Form3 has no default Constructor anymore since you defined one with a string parameter. you need to create a default Constructor like this public Form3(){}.

But Instead of doing all this mess you can handle events of you both forms. Like if Form1 is the main Form then something like this can be done:

In Form1

public string textFromForm2 = string.Empty;
private void openform3_Click(object sender, EventArgs e)
{
    Form3 f3 = new Form3();
    f3.Controls["received_from_form1_textbox"].Text = textFromForm2 ;
    f3.Show();
}

private void OPENFORM2_Click(object sender, EventArgs e)
{
    Form2 f2 = new Form2();
    //I am binding the event to a handler which will save text
    //you should check for null for f2.Controls returned any thing or not, i am leaving it for now
    f2.Controls["send_to_form1_button"].Click += (s,e)=>{
                 txtFromForm2 = f2.Controls["form2_textbox"].Text;
          };
    f2.Show();
}

Update

if you don't want to use Lambadas then bind events like this:

First you will need a reference to the Form2 so declare in your class like this:

Form2 f2;

then bind the event (in place of the lambada i have given before)

f2.Controls["send_to_form1_button"].Click  += new Eventhandler(click_handler);

then somewhere in Form1 class:

protected void click_handler(object sender, EventArgs e)
{
     if(f2 != null)
         txtFromForm2 = f2.Controls["form2_textbox"].Text;
}

similarly for Form3.

edited Feb 19, 2011 at 3:29

answered Feb 18, 2011 at 11:21

Shekhar_Pro

18.5k10 gold badges58 silver badges79 bronze badges

14 Comments

sqlchild Over a year ago

@Shekhar_Pro: dear sir, can you explain me the binding the event code, i dont know whats happening in it? i copied it in my code, but its giving syntax errors?

Shekhar_Pro Over a year ago

i have used Lambda and anonymous delegates to bind event.. if you are using .net 2.0 (Whre they are not supported) then you can do usual binding i have explained in my update

sqlchild Over a year ago

@Shekhar_Pro: sir, my problem hasn't been solved yet, please tell me where to put this code which you have given, am confused totally, am not able to implement a simple process of sending a textbox text from Form2 to Form1 and then from Form1 to form3, FORM1 being the main parent form.

Shekhar_Pro Over a year ago

put this code in Form1. if you still have problems.. Give us your whole code we will see nd tell you what to modify.. (post your code here or on pastebin)

sqlchild Over a year ago

@Shekhar_Pro : sir, i have pasted the code above in my question itself. do i have to make changes in that also?

|

Tony Abrams · Accepted Answer · 2011-02-21 14:52:53Z

public partial class Form1 : Form
{
    string receivefromForm2a;

    public Form1()
    { InitializeComponent(); }

    public void Method_Receive_From_Form2(string receivefromForm2)
    {
        receivefromForm2a = receivefromForm2;
        Form3 f3 = new Form3(receivefromForm2a);
    }

    private void openform2_Click(object sender, EventArgs e)
    {
        Form2 f2 = new Form2();
        f2.Show();
    }

    private void openform3_Click(object sender, EventArgs e)
    {
        Form3 f3 = new Form3(); //**----this line gives error:No overload for method Form3 takes 0 arguments**
        f3.Show();
    }
}

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

    //SENDING VALUE OF TEXTBOX ON FORM2 TO FORM1.

    private void send_to_form1_button_Click(object sender, EventArgs e)
    {
        Form1 f1 = new Form1();
    }
}

public partial class Form3 : Form
{
    public Form3(string receive_from_Form1)
    {
        InitializeComponent();

        received_from_form1_textbox.Text = receive_from_Form1;
    }
}

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