[RESOLVED] sending values to main form from other forms

I declared a public variable in my main form(startup form). then the user clicks on a button and a new form with a textbox appears. the user enters some string in the textbox and clicks a button to close the form. Now i have to show that string in the main form. how?
I cant write form1.label1.text=strresult because
'Object reference not set to an instance of the object'

you need to modify the New() constructor of the ' other ' forms or classes

eg:

VB Code:

Public Class Form2
    Inherits System.Windows.Forms.Form
 
#Region " Windows Form Designer generated code "
 
    '/// this will be used to access it...
    Private frmMain As Form1
 
    Public Sub New(ByVal f As Form)
        MyBase.New()
 
        frmMain = DirectCast(f, Form1)
 
        'This call is required by the Windows Form Designer.
        InitializeComponent()
 
        'Add any initialization after the InitializeComponent() call
 
    End Sub
'/// rest of Form2's stuff here...
'/// then on a sub ( ie:  a button click ) ...
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        '/// pass some data to Form1 ( the main form )
        frmMain.TextBox1.Text = "some stuff passed to Form1 !!!"
    End Sub

to create Form2 ( from form1 when launching it ) ...

VB Code:

'/// when creating Form2 you can now pass the main form ( ie: this form ) as part of the constructor.
        Dim frm2 As New Form2(Me)
        frm2.Show()

thanks a lot