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Copy variable value from a form to a class then to another form

I have form1, class1 and form2.
What I'm trying to do is to get a text from a textbox in form1 and save it to class1 and then again copy it to form2 from class1.
Let me describe via code:
class1.cs
public string username;
form1.cs
class1 user = new class1();
user.username = textbox1.text;
form2.cs
class1 user = new class1();
label1.text = user.username;
The problem is: When I try to call username variable in form2 it returns blank. It just doesn't work. I dont know what I am missing.

If you instantiate a new class1 in form 2, you won't never get your username in label1.

The user in form2 is not the same one that in form1. So in form1 your user including a name, and in form2 it including an initialize value (blank). You can pass this user from form1 to form2 by Session or Cookies.

Make class 1 static. You will be able to call the class from any other instantiated objects, increment (or change) your variable and then retrieve it from any other objects. The synchronized part is something that stops two objects from accessing the incrementCounter() method at the same time. Something like this:
/* This class is thread-safe */
public final class CountHits {
private static int counter;
private static final Object lock = new Object();
public void incrementCounter() {
synchronized (lock) {
counter++;
}
}
public int getCounter() {
return counter;
}
}

Pass value from parent form to child form?

I'm trying to pass a value set in my parent form to a second form. I created a property with a get part in the parent form.
I don't want to do something like:
Form2 secondForm = new Form2(value);
It is an already exiting form and I don't want to keep creating a new form every time I want to pass a value.

See this example.
1-Create a window form application,Declare a public string global variable in Form1 , using this variable we can pass value from Form1 to Form2.
2-Now in form2 ,Create a object for Form1 and Get the value using this object.
See image

You have some possibilities here:
Give a Reference from your first Form as value
Form2 secondForm = new Form2(yourForm1);
So you can access via the getter in your first Form. yourForm1.MyValue;
This seems to be a bit ugly. Better is you create a Interface, which hold your Property and is implemented from you first Form.
public interface IValueHolder
{
public int MyValue {get;}
}
public class FirstForm : Form, IValueHolder
{
public int MyValue{get;}
//Do your form stuff
Form2 form = new Form2(this);
}
So your Form2 just take the Interface and stays independent from Form1. Further you can create a Property on Form2 which you access from Form1. For example if your Property in Form1 changes you set the value from Form2 as well.
public class Form2 : Form
{
public int MyValue{get;set;}
}
public class Form1 : Form
{
private int _myValue;
public int MyValue
{
set
{
if (_myValue != value)
{
form2.MyValue = value;
}
}
}
}
At least you can use a Event maybe. Further you can create a Property on Form2 which holds an Form1 Reference or a IValueHolder as described above.
Hope this helps.

I'm not sure about how you are going to use the Form2 in the parent(let it be frmParent). anyway you can follow any of the steps below:
Define the property in the child form as static so that you can access that by using Form2.frmProperty.
Or define the property as public and then access through the class instance, so that you can access the variable through that instance as long as the instance existed. something like the following:
Form2 secondFormInstance = new Form2();
secondFormInstance.frmProperty = 10;
// at some later points
int childValue = secondFormInstance.frmProperty; // take value from that variable
secondFormInstance.frmProperty++; // update the value
Or you can use like what you specified in the question.

Passing data between forms (and back)

On Form1 I have a label with my total points. In Form2 I made a store were you can purchase things with those points. However I am able to pass the points value to Form2 but I can't figure out how I can send the points value back to Form1.
The code I use to send the value from Form1 to Form2.
Inventory inventory = new Inventory();
inventory.points = points.
I used the search function but since I just started writing code I find most of the given answers too confusing.

Code a constructor for form2 class as below:
public Form2(string strTextBox)
{
InitializeComponent();
label1.Text=strTextBox;
}
On Form1 where you want to call Form2 and pass a value
Form2 frm=new Form2(textBox1.Text);
frm.Show();
Add a property in Form1 to retrieve value from textbox:
public string _textBox1
{
get{return textBox1.Text;}
}
On Form2:
public string _textBox
{
set{label1.Text=value;}
}

Pass the Form1 instance to Form2 when setting the points.
This requires a Form1 public variable in Form2.
e.g
Inventory inventory = new Inventory();
inventory.points = points;
inventory.form1 = this;
and when sending back in Form2
this.form1.points = this.points;
I hope this helps!

How to carry a value in a class through multiple forms

I have a value in my first form of a game which I would like to access on the next 2 forms. This value is saved in a private class. How would I go about doing this?
All help is greatly appreciated.

Create a new constructor in your target Winform class that takes the value as a parameter. Do the same for the subsequent form.
private MyType _value;
public MyForm(MyType myValue) : this()
{
_value = myValue;
}
To show the new form from your original form:
var form = new MyForm(someValue);
form.Show(); // or ShowDialog()

Use get/set to define your value:
Class Form1
int _x; // value you want to access from other class/form
public int YourNumber;
{
get
{
return this._x;
}
set
{
this._x= value;
}
}
Now to access/modify from other class for example Form2:
Class Form2
Form1 form = new Form1();
form.YourNumber = 5; // and it's changed in Form1 also
int y = form.YourNumber; // and you get it from Form1

Use Global Variable concept so that you can access across multiple forms. You can find details from
How to make global variables?
Example:
http://dotnetmirror.com/Articles/wpf/116/global-variables-in-wpf-winforms-mvvm

getting textbox value from another form

I have an TextBox named pass in Form1 that I need to get the value of in form2. I tried this:
public partial class Form1 : Form {
public string GetPass() {
return pass.Text;
}
}
public partial class form2 : Form {
//...
MessageBox.Show(new Form1().GetPass());
}
The above code returns an empty string, why?

You are not showing your actual code as evidenced by the syntax errors etc. - the only logical explanation for your problem is that you are not passing the reference to Form1 correctly to Form2, but create a new form instead - that new form would have the empty textbox.
To further help you, please show how you pass the reference to your Form1 in your actual code.
Edit:
Is see your edit now and above is exactly the problem. You have to pass a Form1 instance to form2 instead of creating a new one, i.e.:
public partial class form2 : Form
{
private Form1 form1;
public form2(Form1 otherForm)
{
form1 = otherForm;
}
public void Foo()
{
MessageBox.Show(form1.GetPass());
}
}

Define one string variable as Public in declaration section
for ex. we have a form with name "frmOne"
public string strVar = string.Empty;
Now, assign the value of TextBox of "frmOne" to that variable from where you are getting the value of Textbox.
for ex.
strVar = Textbox1.Text.ToString();
Now in another form say "frmTwo", you will get access the value of that textbox of "frmOne" something like that (where you want to get the value) :
frmOne frm = new frmOne();
string strValue = frm.strVar;
So, finally strValue local variable of frmTwo contains the value of Textbox of frmOne.

You are creating a NEW form1 where the textbox is likely to be blank, and calling GetPass() on that empty form. You need an instance of the already-opened form1 where the textbox might have a value.

Because you are creating a new instance of Form1 each time you call GetPass().
You need to get the instance of the opened form1 one way or another, and call GetPass on it:
form1.GetPass();
If there is no specifics on the order of creation of form1 and form2, you can use the following to get the instance of form1:
foreach (Form openedForm in Application.OpenForms) {
if (openedForm.GetType() == Form1) {
MessageBox.Show(openedForm.GetPass());
}
}

It's returning empty because you're creating a new instance of the form. Assuming that Form1 is already open somewhere, you need to retrieve the existing instance of Form1 and pull the value from there.

hi you can write this :
public partial class Form1: Form
{
public Form1()
{
InitializeComponent();
}
internal Form2 F2=new form2();
private void CommandBarButton1_Click(object sender, EventArgs e)
{
MessageBox.Show(f2.TextBox1.Text);
}
}