How to use a variable in form1--> form2

[John]

Hi,
I can't find a simple example for a simple(?) problem.

I am working on an application with a variable in form1, that variable
is needed in form2 for a calculation but i can't get that variable in
form2.
Is there a simple method (in VSexpress2005) to get that specific
variable in form2?

TIA,
John

 

[Peter Rilling]

You have to work off of instances of the form, therefore is you want FormA
to access any information from FormB, then FormA has to have a reference to
FormB.

For instance (this is just one way you might do it),

MyFormB formB = new FormB();
MyFormA formA = new Form( formA );

Once a reference to the form is made available, then you can access any
public methods or properties.

 

[Nicholas Paldino [.NET/C# MVP]]

John,

In .NET, forms are object, just like everything else. VB6 would always
create an instance of a form which you could access by the form's type name.

This was never good practice. Instead, make the variable public to form
2 (internal or public if they are in the same assembly), and then pass the
instance of form 1 to form 2 through a method, by setting a property, or
through the constructor. Then, you can store the form as a field in form2
(or just the value you need, you don't have to pass the whole form) and get
the value when you need it.

Hope this helps.

 

[John]

Tnx for the fast response,
however, still missing the point.
Based on a topic @
http://msdn.microsoft.com/library/d...wlkcodegettingvaluefromanotherformvisualc.asp
I created a Form1 with a readonly textBox1 and a button to open Form2.
Form2 contains a textBox1 to insert something and a button to close
Form2.

The code for Form1:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace Form1toForm2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
Form2 getForm2 = new Form2();
getForm2.ShowDialog();
}

public TextBox TextBox1
{
get
{
return textBox1;
}
}
}
}

and the Code for Form2:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace Form1toForm2
{
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
Close();
}

private Form1 otherForm;
private void GetOtherFormTextBox()
{
textBox1.Text = otherForm.TextBox1.Text;
}
}
}


The code above is not working because an event is missing to copy
Form2 textBox text to Form1 textBox
So, what is needed?

TIA,
Greetings,
John

 

[Chris Dunaway]

In order to access the variables of Form1 from Form2, you must *pass a
reference* of Form1 into Form2:

The code for Form1:

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{

**Note the change in the following line:

Form2 getForm2 = new Form2(this);
getForm2.ShowDialog();
}

public TextBox TextBox1
{
get
{
return textBox1;
}
}
}


and the Code for Form2:

public partial class Form2 : Form
{

**Note the change in the constructor for Form2

public Form2(Form1 form1)
{
InitializeComponent(); otherForm = form1;
}

private void button1_Click(object sender, EventArgs e)
{
Close();
}

private Form1 otherForm;
private void GetOtherFormTextBox()
{
textBox1.Text = otherForm.TextBox1.Text;
}
}

Form2's constructor was altered to take a reference to Form1. This was
assigned to your otherForm variable. There are other ways to do this,
this is one way.

 

[John]

Okay after probing your added code it didn't work...
until I found something @
http://www.publicjoe.f9.co.uk/csharp/csharp19.html
where to set the textBox1 from privat (default) to public, that did
the job...
anyway, thanks for the support on this (simple) brainteaser...

John.