Develop Reference

Is there any other way to access open forms in C#?

Application.OpenForms["formname"];
Is there any other way to access an open form. My application doesn't see this form although it is opened. I dont know why.

Isn't really necessary a name to get an open form.
You can get the form you want by index:
Form frm = Application.OpenForms[0] //Will get the main form
Form frm = Application.OpenForms[1] //Will get the first child
Forms in the OpenForms collection are ordered in the same way that you create it
Otherwise, an alternative is to save a reference to the form and then accessing it by this reference.
//Where you want to save the reference:
Form theForm;
//Where you create the form:
myClass.theForm = new MyForm();
//Where you want to get that form:
MessageBox.Show(myClass.theForm.Caption);
(myClass is the class that will hold your reference to the form, supposing you are accessing it from different classes)
(Also, see if you are affected by this: Application.OpenForms.Count = 0 always)

I recommend you to firstly debug your code to check what is the Form actual name which you want to load:
foreach (Form form in Application.OpenForms) {
string name = form.Name; //check out this name!!
//print, or anything else will do, you only want to get the name
//note that you should be able to get any form as long as you get its name correct
}
And then, once you know what is wrong with your code, simply do:
Form form = Application.OpenForms[name]; //use the same name as whatever is available according to your debug
To get your form.
To check more on the possible bugs, See Hans Passant's Post

You have to instanciate first a Form. after that you have access to it:
Form1 formname = new Form1();
Application.Run(formname);
// access to form by formname.yourproperty

To access the form using this property your form must have a Name.
Remember its not the instance name nor the the form Text:
Form1 f1 = new Form1(); //not "f1" is the "Name"
f1.Text = "it is title of the form"; //neither "Text" is the "Name"
f1.Name= "its the name"; //it is the "Name"
Sample:
frm_myform form1 = new frm_myform();
frm_myform.Name = "form1";

How can I save a dynamically created user control if it contains some buttons in c#?

I am new to C#. I am using windows forms and I have Form1 which contains 2 buttons ( one to create user control at run time and the other creates buttons on user control at run time).
This code creates user control and FlowLayoutPanel (to organize button position) if you click add_UserControl button. And then it creates buttons on FlowLayoutPanel if you click Add_Buttons button and it is all done at run time.
Now in Form1 let's say I created user control and FlowLayoutPanel and then created 5 buttons , how can I save the properties/details of this user control with its FlowLayoutPanel and 5 buttons in SQL database so I can use them later when I run the program? I have been thinking about an idea and I reached the internet but no luck.
Any idea? Please help me. Thank you
public partial class Form1 : Form
{
FlowLayoutPanel FLP = new FlowLayoutPanel();
UserControl uc = new UserControl();
private void add_UserControl_Click(object sender, EventArgs e)
{
uc.Height = 700;
uc.Width = 900;
uc.BackColor = Color.Black;
Controls.Add(uc); //add UserControl on Form1
FLP.Height = 600;
FLP.Width = 800;
FLP.BackColor = Color.DimGray;
uc.Controls.Add(FLP); // add FlowLayoutPanel to UserControl
}
private void Add_Buttons_Click(object sender, EventArgs e)
{
//####### add buttons to FlowLayoutPanel ############
Button dynamicButton = new Button();
dynamicButton.Height = 50;
dynamicButton.Width = 200;
dynamicButton.BackColor = Color.Green;
dynamicButton.ForeColor = Color.Blue;
dynamicButton.Text = "";
FLP.Controls.Add(dynamicButton);
}
}

OK, First you need to create a class that will represent one of the buttons with the properties you need.
class MyButton
{
public string ButtonText {get;set;}
}
Everytime you click and create a button, you actually create an object of this class and add it to a collection or list. Then you would have some other code watching over the collection, and every time it gets a new entry, it creates a new button and sets its Button text to the text property. when a member of list is gone, it removes the button.
If you need more properties to be remembered (color, size, font, ...) you add them to the class as well. If you need for other controls, as well, .... you can always create common parent controls.
Simple.
If you want to be able to reload it, you could define the MyButton class as serializable and store it in xml file, and upon build, reload it.
You should watch into WPF and it's MVVM pattern. It's pretty much similar to it. Also have a look into command pattern, usefull pattern when it commes to this.

You can remember the FlowLayoutsPanels in one SQL table and in another table you could save the buttons which belong to these FlowLayoutPanels.
On Form Load or Application Load, you could check if there are already FlowLayoutPanels and correspending Buttons do exist in the SQL db and if yes then create them, else do nothing.

C# Can't change labels and button properties from a dialogbox

I have my main form and a dialogbox which is called from main. In my main form I have a label and a button that which properties I can't change. I'm using Visual Studio 2015, not sure if there is a bug regarding this. I also made sure my label and button are set to public to modify.
Code: (this is from the dialog box, this has a list box the function is triggered at selectindexchange)
else if ((short)lbDiscountTypes.SelectedValue == 2) //Senior
{
frm_Main main = new frm_Main();
main.VAT = false;
main.labelStatus.Text = "NON-VAT (SENIOR)";
main.labelStatus.BackColor = System.Drawing.Color.IndianRed;
main.labelStatus.ForeColor = System.Drawing.Color.WhiteSmoke;
main.btnNonVat.Enabled = false;
main.btnNonVat.BackColor = System.Drawing.Color.SlateGray;
main.btnNonVat.ForeColor = System.Drawing.Color.Navy;
main.labelVatAmount.Text = 0.00m.ToString();
main.Dispose();
//INQUIRE DISCOUNT TYPES
var Discount = GC.CSHR_DiscountTypes.Where(Filter => Filter.DiscountCode == (short)lbDiscountTypes.SelectedValue);
decimal DP = 0.00m;
foreach (var item in Discount)
{
DP = item.DiscountPercentage;
}
foreach (var item in GC.CSHR_SORepo
.Where(Filter => Filter.Machine == MACHINE
&& Filter.SalesOrderNum == SALESORDERNUM
&& Filter.First_SRP == Filter.IMFSRP))
{
item.DiscountAmount = (item.SoldSRP * DP) / 100;
item.TotalAmount = (item.Quantity * item.SoldSRP) - item.DiscountAmount;
item.VATableSalesOnTotalAmount = (item.Quantity * item.SoldSRP) - item.DiscountAmount;
item.VATRate = 0.00m;
GC.SaveChanges();
}
Close();
}
The code below //INQUIRE DISCOUNT TYPES works well but not the one on top.
I've used debug mode to check if the lines are not being skipped over and they aren't.

You should pay attention to:
You are creating a new instance of your main form that you don't need (while it is open behind the dialog), so you need to get it not create a new instance
You are disposing the main form you created. main.Dispose();
In fact you are creating a new instance of main form and assigning values to those controls and then dispose it. While and instance of yor main form that you expect to see changes on it, is open and untouched behind your dialog.
To set value of those controls you can do one of these ways:
Option 1
Make your labelStatus and btnNonVat public. Open your main form in designer and select labelStatus and btnNonVat and in property grid, set Modifier to public. Then write this code:
//var main = Application.OpenForms.OfType<frm_Main>().FirstOrDefault();
var main = (frm_Main)Application.OpenForms["frm_Main"];
main.labelStatus.Text = "NON-VAT (SENIOR)";
main.labelStatus.BackColor = System.Drawing.Color.IndianRed;
main.labelStatus.ForeColor = System.Drawing.Color.WhiteSmoke;
main.btnNonVat.Enabled = false;
main.btnNonVat.BackColor = System.Drawing.Color.SlateGray;
main.btnNonVat.ForeColor = System.Drawing.Color.Navy;
main.labelVatAmount.Text = 0.00m.ToString();
Option 2
Pass an instance of your frm_Main to your dialog and work with it.
Option 3
After closing the dialog, use values from dialog and set values of your main form

Looks like you are trying to create new form using frm_Main main = new frm_Main(); syntax. All you need to do is get the instance of your current form.
var _currentMainForm= Application.OpenForms[0];
or if you have given name to your form
var _currentMainForm = Application.OpenForms["MainFormName"];
Once you get the reference you can perform all your label updates.

The code on top creates a new form, changes the labels and then disposes the form.
I think you should change the labels of the existing form.

Like in the other answer said you are setting properties of controls into a new Form object and not in the form where you come from.
You should pass the form object into the parameters of the dialog, something like:
void myDialog(frm_Main callingForm)
{
callingForm.Textbox1.Text = "abc";
}
And call it from you main form like this
...
myDialog(this);

Creating Edit dialog box in Windows Forms C#

I have Form1.cs which has two buttons say "ADD" and "EDIT".
Clicking "ADD" shows dialog Form2.cs.
Form2 has a TextBox and a ComboBox. Say we enter value "A" in textbox and select "A" from ComboBox.
Then close Form2.
Then when EDIT button is clicked on Form1, Form2 should show up with "A" in textbox and "A" selected in ComboBox.
This is a simple explanation. The real form I am using has around 10-12 different controls including combobox, checkbox, textbox etc.
My main doubt is where and how do we save these control values.
Is there a specific approach to this type of DialogBoxes that I am missing?

Create class, that would store values that you want to pass (let's call it Foo).
Form2 should then have a property. In the setter of the property, set controls:
public partial class Form2 : Form
{
private Foo _bar;
public Foo Bar
{
set
{
_bar = value;
//set your controls here
}
}
On Edit button, set property like this:
Form2 form2 = new Form2();
form2.Bar = bar; //bar contains values to edit
Then put a Save button on Form2, that would save values back from controls to this object.
For every control I would have a field in Foo class, eg. string for textboxes, bool for checkboxes and enum or int for comboboxes (where integer value would equal selected index).
Alternatively, you could use Dictionary class instead and have key and value pair for every control.
You can also have some enum, if your form looks or behaves differently in New and Edit mode.

Your Dialog Form should have a field containing the properties/fields you want, a copy a business object for example. Then you pass it or initialize it in your dialog constructor or Load, depending the behavior you want. From there you can create / initialize your controls.
If you want a built in system you may wanna take a look to the PropertyGrid (which you could embedded in a dialog (to fit your question))

Do you want to just load the last value user entered there?
For instance he writes "text" on the textbox and chooses "A" combobox it should be pre-selected next time you open it?
Edit: Then instead of closing it using Form.Close make it so that it hides. Form1.Hide. Next time it opens values are still saved. Unless application has been closed. In the other hand, users might click on the close button in the windows form. You can either make it "unclickable" throught proprieties or just configure it using events i think.

Create a method on Form2, where you will set values into textBox and select an item in comboBox. Call this method just after instantiating form2 and before showing it.
Example:
public Form2()
{
InitializeComponent();
comboBox1.Items.AddRange(new string[] { "a", "b", "c" });//fill comboBox your way on a loading time
}
public void UpdatingControls(string a, string b)
{
textBox1.Text = a;
comboBox1.SelectedText = b;
}
//on form2;
Form1 f2;
private void OpenForm2Button_Click(object sender, EventArgs e)
{
f2 = new Form2();
f2.UpdatingControls("a", "b"); //a will go into textBox, b will be choosen in comboBox
}

public Form2(string form1Textbox)
{
InitializeComponent();
form2Textbox.Text = form1Textbox;
}

In C#, is there a way to open a 2nd form with a tab selected?

Does anyone know a way to open a 2nd form in a .NET application with a certain tab selected in a tab control on that form?
This is what my current code looks like which just opens the form:
SettingsForm TheSettingsForm = new SettingsForm(this);
TheSettingsForm.Show();
SettingsForm.cs is the name of the 2nd form to be opened.
Thanks in advance,

You just need to expose a property on your form that allows the calling code to set the desired tab. You might do it just by index like this:
var form = new SettingsForm(this);
form.SelectedTab = 2;
form.Show();
The property on the form would just set the appropriate property on the tab control:
public int SelectedTab
{
get { return _tabControl.SelectedIndex; }
set { _tabControl.SelectedIndex = value; }
}

Do something like this:
SettingsForm TheSettingsForm = new SettingsForm(this);
TheSettingsForm.TabPanel.SelectedIndex = SettingsFormTabIndexes.MyDesiredTab;
TheSettingsForm.Show();
where you've made a property in TheSettingsForm that exposes the tab control and SettingsFormTabIndexes is a friendly enum naming all the tabs by index.

Add an event handler to the TabControl.SelectedIndexChanged event.
myTabControl.SelectedIndexChanged += myTabControl_SelectedIndexChanged;
private void myTabControl_SelectedIndexChanged(object sender, EventArgs e) {
TabControl tc = sender as TabControl;
if (tc.SelectedIndex == indexOfTabToShowFormOn) {
TheSettingsForm.Show();
}
}