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How to modify label text in C# forms

(I am very new to C#) I am creating a forms application, and the purpose is to get a string from a Web API, then put that text onto a label. I have successfully gotten the data from the Web, but when I try to update the label, I have no luck.
I have debugged and found that my method inside my class Is executing, but just not setting the label's text. As you can see below, I tried to use this.resultLabel.text = str;. Here's the classes:
Program.cs (not the form cs file)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Net.Http;
using System.Net;
using System.IO;
namespace WebsiteAPITest
{
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
class PostManager
{
public void setupClient()
{
HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create(string.Format("https://yakovliam.com/phpApi/csTest.php"));
WebReq.Method = "GET";
HttpWebResponse WebResp = (HttpWebResponse)WebReq.GetResponse();
string respStr;
using (Stream stream = WebResp.GetResponseStream()) //modified from your code since the using statement disposes the stream automatically when done
{
StreamReader reader = new StreamReader(stream, System.Text.Encoding.UTF8);
respStr = reader.ReadToEnd();
}
MessageBox.Show(respStr);
Form1 form = new Form1();
form.SetResultLabel(respStr);
}
}
}
Actual form class (Form1.cs)
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 WebsiteAPITest
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void GetButton_Click(object sender, EventArgs e)
{
PostManager postManager = new PostManager();
postManager.setupClient();
}
public void SetResultLabel(string str)
{
this.resultLabel.Text = str;
this.resultLabel.Refresh();
}
}
proof of label name:

Inside setupClient you call Form1 form = new Form1(); that creates a second Form1 which you never display, then you call SetResultLabel(respStr) inside this second form you never display, then you leave the method and discard it.
If you want to call SetResultLabel of your calling form, you have to pass the calling form to setupClient:
public void setupClient(Form1 callingForm)
{
...
callingForm.SetResultLabel(respStr);
Then inside your Form1:
postManager.setupClient(this);
It's quite dangerous to pass forms to other methods; a better design is to have the other method return data to your form:
public string setupClient()
{
...
return respStr;
}
And inside Form1:
SetResultLabel(postManager.setupClient());

How do I create event between two projects?

I created two projects(Proj_1,Proj_2), Proj_1 contains Proj_1_Program.cs and ProjectOneClass.cs, Proj_2 contains Proj_2_Program.cs,and I need OnInformed trigger both Informed1 and Informed2 this is how I got so far:
//Proj_1_Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace CrossProjectEvent
{
class Proj_1_Program
{
static void Main(string[] args)
{
ProjectOneClass obj1 = new ProjectOneClass();
obj1.Inform += new EventHandler(Informed1);
obj1.InformNow();
Console.ReadLine();
}
private static void Informed1(object sender, EventArgs e)
{
Console.WriteLine("Informed1");
}
}
}
//ProjectOneClass.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace CrossProjectEvent
{
public class ProjectOneClass
{
public event EventHandler Inform;
public void InformNow()
{
OnInformed(new EventArgs());
}
private void OnInformed(EventArgs eventArgs) // I want this method both trigger Informed1 and Informed2
{
if (Inform != null)
{
Inform(this, eventArgs);
}
}
}
}
//Proj_2_Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using CrossProjectEvent;
namespace Proj_2
{
public class ProjectTwoClass
{
public ProjectOneClass obj_proj_1;
public ProjectTwoClass()
{
obj_proj_1 = new ProjectOneClass();
obj_proj_1.Inform += new EventHandler(Informed2);
}
private static void Informed2(object sender, EventArgs e)
{
Console.WriteLine("Informed2");
}
}
class Project2
{
static void Main(string[] args)
{
}
}
}
But it seems like only Informed1 being triggered, so how to fix this? thanks!

This is a typical problem requiring inter-process communication. There are a billion different techniques and approaches possible for it.
One solution would be to use Remoting using named pipes (Sample), but also TCP and NetSockets are possible. This might be one of the simplest solutions.
If you are building a larger application requiring a lot of inter-process communication, the actor model, especially the AKKA.NET libary, would be worth mentioning.
But these are just a few of the options you have.

How to start a process/application on windows connection change event using C#

I can detect the network connection change event while running a C# code, how would I register an exe when Windows detects this event. What all details would I need. Below is how I am using this :
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.NetworkInformation;
namespace ConsoleApplication2
{
class Program
{
static void Main(string[] args)
{
testing t = new testing();
Console.Read();
}
}
public class testing{
public testing()
{
NetworkChange.NetworkAvailabilityChanged += new NetworkAvailabilityChangedEventHandler(NetworkChange_NetworkAvailabilityChanged);
}
void NetworkChange_NetworkAvailabilityChanged(object sender, NetworkAvailabilityEventArgs e)
{
if (e.IsAvailable)
{
Console.WriteLine("network is available");
}
}
}
}

What you could maybe do is in your method that is triggered to start a new process and execute your exe

C# - Tier Separation - How to use these delegates?

Here's the relevant code:
ClickMeGame.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ClassLibrary
{
public class ClickMeGame
{
public OnClickMe onClickMeCallback;
public int score;
public ClickMeGame()
{
score = 0;
}
private void IncrementScore()
{
score++;
}
}
}
ClickMeCallBackDefinitions.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ClassLibrary
{
public delegate void OnClickMe();
}
MainWindow.cs (Windows Form)
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;
using ClassLibrary;
namespace ClickMe
{
public partial class mainWindow : Form
{
private ClickMeGame game;
public mainWindow()
{
InitializeComponent();
game = new ClickMeGame();
game.onClickMeCallback = clickMeButton_Click();
}
private void clickMeButton_Click(object sender, EventArgs e)
{
UpdateUI();
}
private void UpdateUI()
{
scoreLabel.Text = string.Format("The score is: {0}", game.score);
}
}
}
So what I'm trying to do is, when the user clicks a button present on the form, I want a label on the form to update with the game score which increments with every click.
I'm learning about/want to be able to do this with delegates in that I want to separate the project into 2 tiers; Presenation and Logic. I know it's unnecessary to do so, but I'd like to make it such that when you click the button, the Windows Form receives information about the game score via delegates/callback methods. I'm unsure how to do this, but I tried making the callback definition and referencing it, but I'm lost from there.

Assuming that the UI button uses the click event clickMeButton_Click then here you go.
public partial class mainWindow : Form
{
private ClickMeGame game;
public mainWindow()
{
InitializeComponent();
game = new ClickMeGame();
game.onClickMeCallback = param => UpdateUI();
}
private void clickMeButton_Click(object sender, EventArgs e)
{
game.onClickMeCallback.Invoke();
}
private void UpdateUI()
{
scoreLabel.Text = string.Format("The score is: {0}", game.score);
}
}

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.