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C# An object reference is required for the non-static field, method, or property 'variables.rhifAnfoneb' [duplicate]

This question already has answers here:
Using list between forms
(3 answers)
Closed 2 years ago.
I am trying to get a list from another form. I have made the list public and put it in its own class to no avail.
Form1:
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.Common;
using System.Configuration;
namespace eAnfonebu
{
public class variables
{
public List<int> rhifAnfoneb = new List<int>();
public List<int> rhifArcheb = new List<int>();
public string[] ddydiadArcheb;
public string[] enwArchebwr;
public string[] eBost;
public int[] gair;
public decimal[] prisMilGair;
}
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void createNew_Click(object sender, EventArgs e)
{
Form2 f2 = new Form2();
f2.ShowDialog(); // Shows Form2
}
}
}
Form2 (addInvoice):
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace eAnfonebu
{
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
private void AddInvoice_Click(object sender, EventArgs e)
{
try
{
variables.rhifAnfoneb.Add(variables.rhifAnfoneb[variables.rhifAnfoneb.Length - 1] + 1);
}
catch
{
variables.rhifAnfoneb.Add(1);
}
}
}
}
I am getting the error (An object reference is required for the non-static field, method, or property 'variables.rhifAnfoneb') in
try
{
variables.rhifAnfoneb.Add(variables.rhifAnfoneb[variables.rhifAnfoneb.Length - 1] + 1);
}
catch
{
variables.rhifAnfoneb.Add(1);
}
I am sorry for different languages in same code but I am billingual and sometimes I set out to make an app in one language but then it slowly morphs to another.
If awnsering could you please awnser as simply as you could because I am new to c#
Any help would be greatly appreciated.
Eoin

change
public class variables
to
public static class variables
And make all fields static as well. Because, A static class can only contain static data members, static methods.
or
create an instance of variables
variables v = new variables();
v.rhifAnfoneb.Add(variables.rhifAnfoneb[variables.rhifAnfoneb.Length - 1] + 1);
Reference
Static Classes and Static Class Members

I am getting the error (An object reference is required for the
non-static field, method, or property 'variables.rhifAnfoneb') in
Instantiate the Class then use the its members
public static Variables variabs {get;set;}
public Form2()
{
variabs = new variables();
InitializeComponent();
}
private void AddInvoice_Click(object sender, EventArgs e)
{
try
{
variabs.rhifAnfoneb.Add(variables.rhifAnfoneb[variables.rhifAnfoneb.Length - 1] + 1);
}
.
.
}
To Access from Form1
public static Variables variabs {get;set;}
public Form1()
{
variabs= Form2.variabs;
}

How to declare an instance of another class?

I have following question, right now like 2 minutes ago a guy posted his code.
He couldn't use his instance obj , and I don't know why he deleted his question.
He had also some usings, I think he had using static N.Form1
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApp1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
int Y(int a)
{
a = 10;
Console.WriteLine(a);
return a;
}
}
}
}
namespace WindowsFormsApp1
{
class Class1
{
N.Form1 obj = new N.Form1();
public void X(int a)
{
var v = obj.Y(a);
Console.WriteLine(v);
}
}
}
So first I've seperate the method, and made it public so I can create instance and use it in another class.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public int Y(int a)
{
a = 10;
Console.WriteLine(a);
return a;
}
}
And then instead of using N.From1, I used the namespace for declaring instance WindowsFormsApp1.Form1 obj = new WindowsFormsApp1.Form1();
My Class1 looks like this now:
class Class1
{
WindowsFormsApp1.Form1 obj = new WindowsFormsApp1.Form1();
public void X(int a)
{
var v = obj.Y(a);
Console.WriteLine(v);
}
}
So there isn't any error, and my question is, is this the right way to declare and instance and use it later? Also are you allowed to use the namespace ?
Thanks,

Passing txtBox values between forms

I have always had trouble with this issue, i think i need to learn how it works, i have FormMain (my main form) and a second form (FormAddUrls) when i open form2 (FormAddUrls) i want to pass the multitextbox value back to the main form (FormMain)
I know in VB it's as simple as saying: FormMain.txtBoxUrls.Text = finalOutput; but not as easy in C#.
(form1) - FormMain
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Windows.Forms;
using WraithProjectCreator;
using IronPdf;
using System.Text;
namespace GSAProjectCreator
{
public partial class FormMain : Form
{
private IniParser m_Parser = null;
public FormMain()
{
InitializeComponent();
}
private void btnShowUrlsForm_Click(object sender, EventArgs e)
{
FormAddUrls fau = new FormAddUrls();
fau.Show();
}
}
}
(form2) - FormAddUrls
using GSAProjectCreator;
using System;
using System.Text;
using System.Windows.Forms;
namespace WraithProjectCreator
{
public partial class FormAddUrls : Form
{
public FormAddUrls()
{
InitializeComponent();
}
private void btnAddUrls_Click(object sender, EventArgs e)
{
StringBuilder builder = new StringBuilder();
builder.Append("{");
foreach (string line in txtBoxURLsMass.Lines)
{
//Helpers.returnMessage(line);
builder.Append(line + "|");
}
builder.Append("}");
string finalOutput = "";
if (builder.ToString().Contains("|}")) {
finalOutput = builder.ToString().Replace("|}", "}");
}
//FormMain.txtBoxUrls.Text = finalOutput;
this.Close();
}
}
}
I have ommited a lot of form1's code to leave the basic structure, i'm trying to pass back finalOutput from form2 to form1 (the txtBoxUrls.Text) text box, any help would be appreciated.

It depends on how you want to use the main form - you could have a static property which you could set (which would update the text for all main form instances).
If you only have one main form, and have a reference to it when you create the FormAddUrls object then you should just change the constructor to accept a MainForm (or as generic a type as possible), store the reference as a field and update the property on it when the button is clicked:
public partial class FormAddUrls : Form
{
private readonly Form _parentForm;
public FormAddUrls(MainForm parent)
{
_parentForm = parent;
InitializeComponent();
}
private void btnAddUrls_Click(object sender, EventArgs e)
{
StringBuilder builder = new StringBuilder();
builder.Append("{");
foreach (string line in txtBoxURLsMass.Lines)
{
//Helpers.returnMessage(line);
builder.Append(line + "|");
}
builder.Append("}");
string finalOutput = "";
if (builder.ToString().Contains("|}")) {
finalOutput = builder.ToString().Replace("|}", "}");
}
if(_parentForm != null)
_parentForm.txtBoxUrls.Text = finalOutput;
this.Close();
}
}

Return Value Between Classes

How do I get a button click on a form to send the return of a called method to another class? Here is the pseudo code of what I have and any help would be greatly appreciated...
[Class Library]
using System;
using System.Runtime.InteropServices;
using System.Text;
using System.Collections.Generic;
using System.Linq;
namespace Auto
{
GUID Info
public interface IAuto
{
string SendToOtherApp();
}
COM Info
public class Auto : IAuto
{
public string tbox1;
NAVForm frm1 = new NAVForm();
public Auto()
{
}
public string SendToOtherApp()
{
frm1.ShowDialog();
tbox1 = NAVForm.UseThis();
return tbox1;
}
}
}
[Form]
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Auto
{
public partial class NAVForm : Form
{
public NAVForm()
{
InitializeComponent();
}
private void NAVForm_Load(object sender, EventArgs e)
{
}
private void button2_Click(object sender, EventArgs e)
{
UseThis(textBox1.Text);
}
public string UseThis(string txt)
{
if (txt.Trim().Length != 0)
{
return txt;
}
else
{
return "didn't work";
}
}
}
}
I want to get the return value from public string UseThis(string txt) into public string SendToOtherApp() which is visible to the other system that is calling this.
I am obviously new to C# so I am also very open to an overall critique of the project and best practices.

This is what I have done and it works great. In our ERP I run the codeunit, which calls the automation variable which is tied to the "OpenThis()" method. My form opens, I enter text in the textbox, click OK, it closes the from and the ERP pops a messagebox displaying the text from the message box. What do you C# experts think about this build? I am very interested in your thoughts on this solution so please let me know.
Class Library.....
using System;
using System.Runtime.InteropServices;
using System.Text;
using System.Collections.Generic;
using System.Linq;
namespace NavAutomation
{
[InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
[Guid("5D83B4FE-45E6-410E-A075-AD635F5F0354")]
[ComVisible(true)]
public interface INavAutomation
{
string HelloWorld();
object OpenThis();
}
[ComVisible(true)]
[Guid("B7806CE5-862A-4407-9A3E-14CE8A9FB83A")]
[ClassInterface(ClassInterfaceType.None)]
public class NavAutomation : INavAutomation
{
public NavAutomation()
{
}
public object OpenThis()
{
using (var form = new NAVForm())
{
var result = form.ShowDialog();
return form.RetVal1;
}
}
}
}
Form.....
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace NavAutomation
{
public partial class NAVForm : Form
{
public NAVForm()
{
InitializeComponent();
}
private void NAVForm_Load(object sender, EventArgs e)
{
}
public string RetVal1 { get; set; }
private void button2_Click(object sender, EventArgs e)
{
if (textBox1.Text.Trim().Length != 0)
{
this.RetVal1 = textBox1.Text;
}
else
{
this.RetVal1 = "didn't work";
}
this.Close();
}
}
}

I am not sure if i got your goals right but here is the code that when called from a from, shows another modal form with a textbox, you enter a value into that textbox and close this modal form to find that value in that textbox returned to the first form that called for the show of the modal form.
CLASS LIBRARY
using System;
using System.Runtime.InteropServices;
using System.Text;
using System.Collections.Generic;
using System.Linq;
namespace Auto
{
public interface IAuto
{
string SendToOtherApp();
}
public class Auto : IAuto
{
public string tbox1;
NAVForm frm1 = new NAVForm();
public Auto()
{
}
public string SendToOtherApp()
{
frm1.ShowDialog();
tbox1 = frm1.UseThis(frm1.textBox1.Text);
return tbox1;
}
}
}
A FROM THAT CALLS TO SHOW A MODAL FORM
namespace Auto
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Auto auto = new Auto();
string returnedString = auto.SendToOtherApp(); // the string filled at the modal form text boxed will be returned to this variable
}
}
THE FORM THAT WILL BE SHOWED AS MODAL FORM
namespace Auto
{
public partial class NAVForm : Form
{
public NAVForm()
{
InitializeComponent();
}
public string UseThis(string txt)
{
if (txt.Trim().Length != 0)
{
return txt;
}
else
{
return "didn't work";
}
}
private void button1_Click(object sender, EventArgs e)
{
UseThis(textBox1.Text);
}
}
}
Please note that the access modifier of textBox1 at NAVForm should be set to public in order for it to be visible to class Auto
Let me know if i misunderstood something to correct it.

How to create a Sleep method for my application

I want to create a method which makes my application wait X number of seconds, then continues on down a line of scripts. For example, this is the code that I have so far, after reading many similar help topics:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
methods.WriteTextToScreen(label1, "Hello!");
methods.sleepFor(1);
methods.WriteTextToScreen(label1, "Welcome!");
methods.sleepFor(1);
methods.WriteTextToScreen(label1, "Allo!");
}
public class methods
{
public static int timeSlept;
public static void WriteTextToScreen(Label LabelName, string text)
{
LabelName.Text = text;
}
public static void sleepFor(int seconds)
{
timeSlept = 0;
System.Timers.Timer newTimer = new System.Timers.Timer();
newTimer.Interval = 1000;
newTimer.AutoReset = true;
newTimer.Elapsed += new System.Timers.ElapsedEventHandler(newTimer_Elapsed);
newTimer.Start();
while (timeSlept < seconds)
{
Application.DoEvents();
}
Application.DoEvents();
}
public static void newTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
timeSlept = IncreaseTimerValues(ref timeSlept);
Application.DoEvents();
}
public static int IncreaseTimerValues(ref int x)
{
int returnThis = x + 1;
return returnThis;
}
}
}
}
What I want to do is have my program do the methods.WriteTextToScreen(label1, "Hello!")
then wait for 1 second, then continue on in the same fashion. The problem is that the Form I'm displaying the text on doesn't show up at all until it has written "Allo!" onto the screen, so the first time it appears it already says that. Am I doing something wrong, or is there just no way to do this?

The form doesn't show until it has been constructed i.e. all the code in Form1 is run. See here for info on form constructors: http://msdn.microsoft.com/en-us/library/system.windows.forms.form.form.aspx
To fix your problem you could move the writeTextToScreen and sleep code into the forms on load method. See http://msdn.microsoft.com/en-us/library/system.windows.forms.form.onload.aspx