I'll start by saying that i am no beginner in C# but not very much more and need help returning value to main. Or rather tell me what is the "correct" way.
I want to return a fail value (simply -1) from the application, in case of any exception and ending up in a catch. In that case passing info to main to return -1.
The way I solved it was by just adding a static global variable mainReturnValue (to be able to access it from main), and setting its value to -1 in the catches.
Is that a correct way of doing it, based on my current code?
If anyone is wondering the applications is executed without user interaction and that's why I need to catch the exit state. The form/GUI just displays info about the progress, in case it's started manually.
namespace ApplicationName
{
/// <summary>
/// Summary description for Form1.
/// </summary>
public class Form1 : System.Windows.Forms.Form
{ ...
static int mainReturnValue = 0; //the return var
static int Main(string[] args)
{
Application.Run(new Form1(args));
return mainReturnValue; //returning 0 or -1 before exit
}
private void Form1_Load(object sender, System.EventArgs e)
{
the code..in turn also calling some sub functions such as DoExportData...and I want to be able to return the value to main from any function...
}
private int DoExportData(DataRow dr, string cmdText)
{
try { ... }
catch
{ mainReturnValue = -1; }
}
Thanks.
You could do this:
static int Main(string[] args)
{
Form1 form1 = new Form1(args);
Application.Run(form1);
return form1.Result;
}
and then define a property on your Form1 class, whose value you can set after the DoExportData method executes. For example:
public int Result { get; private set; }
private void Form1_Load(object sender, System.EventArgs e)
{
Result = DoExportData(...);
}
private int DoExportData(DataRow dr, string cmdText)
{
try
{
...
return 0;
}
catch
{
return -1;
}
}
How to: Get and Set the Application Exit Code from MSDN.
By the way, an exit code of 0 indicates success, while anything > 0 indicates an error.
I would add also something like this
AppDomain currentDomain = AppDomain.CurrentDomain;
currentDomain.UnhandledException += new UnhandledExceptionEventHandler(CrashHandler);
static void CrashHandler(object sender, UnhandledExceptionEventArgs args) {
mainReturnValue = -1;
}
Just to be sure that even unhandled exceptions are "handled" by your application in a way you want, cause I presume your app is not only about one WindowsForm.
Related
Consider:
namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
//int[] val = { 0, 0};
int val;
if (textBox1.Text == "")
{
MessageBox.Show("Input any no");
}
else
{
val = Convert.ToInt32(textBox1.Text);
Thread ot1 = new Thread(new ParameterizedThreadStart(SumData));
ot1.Start(val);
}
}
private static void ReadData(object state)
{
System.Windows.Forms.Application.Run();
}
void setTextboxText(int result)
{
if (this.InvokeRequired)
{
this.Invoke(new IntDelegate(SetTextboxTextSafe), new object[] { result });
}
else
{
SetTextboxTextSafe(result);
}
}
void SetTextboxTextSafe(int result)
{
label1.Text = result.ToString();
}
private static void SumData(object state)
{
int result;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
setTextboxText(result);
}
delegate void IntDelegate(int result);
private void button2_Click(object sender, EventArgs e)
{
Application.Exit();
}
}
}
Why is this error occurring?
An object reference is required for the nonstatic field, method, or property 'WindowsApplication1.Form1.setTextboxText(int)
It looks like you are calling a non static member (a property or method, specifically setTextboxText) from a static method (specifically SumData). You will need to either:
Make the called member static also:
static void setTextboxText(int result)
{
// Write static logic for setTextboxText.
// This may require a static singleton instance of Form1.
}
Create an instance of Form1 within the calling method:
private static void SumData(object state)
{
int result = 0;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
Form1 frm1 = new Form1();
frm1.setTextboxText(result);
}
Passing in an instance of Form1 would be an option also.
Make the calling method a non-static instance method (of Form1):
private void SumData(object state)
{
int result = 0;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
setTextboxText(result);
}
More info about this error can be found on MSDN.
For this case, where you want to get a Control of a Form and are receiving this error, then I have a little bypass for you.
Go to your Program.cs and change
Application.Run(new Form1());
to
public static Form1 form1 = new Form1(); // Place this var out of the constructor
Application.Run(form1);
Now you can access a control with
Program.form1.<Your control>
Also: Don't forget to set your Control-Access-Level to Public.
And yes I know, this answer does not fit to the question caller, but it fits to googlers who have this specific issue with controls.
You start a thread which runs the static method SumData. However, SumData calls SetTextboxText which isn't static. Thus you need an instance of your form to call SetTextboxText.
Your method must be static
static void setTextboxText(int result)
{
if (this.InvokeRequired)
{
this.Invoke(new IntDelegate(SetTextboxTextSafe), new object[] { result });
}
else
{
SetTextboxTextSafe(result);
}
}
Credit to #COOLGAMETUBE for tipping me off to what ended up working for me. His idea was good but I had a problem when Application.SetCompatibleTextRenderingDefault was called after the form was already created. So with a little change, this is working for me:
static class Program
{
public static Form1 form1; // = new Form1(); // Place this var out of the constructor
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(form1 = new Form1());
}
}
I actually got this error because I was checking InnerHtml for some content that was generated dynamically - i.e. a control that is runat=server.
To solve this I had to remove the "static" keyword on my method, and it ran fine.
From my looking you give a null value to a textbox and return in a ToString() as it is a static method. You can replace it with Convert.ToString() that can enable null value.
Make the function static. This must solve your problem.
The essence, and solution, to your problem is this:
using System;
namespace myNameSpace
{
class Program
{
private void method()
{
Console.WriteLine("Hello World!");
}
static void Main(string[] args)
{
method();//<-- Compile Time error because an instantiation of the Program class doesnt exist
Program p = new Program();
p.method();//Now it works. (You could also make method() static to get it to work)
}
}
}
Consider:
namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
//int[] val = { 0, 0};
int val;
if (textBox1.Text == "")
{
MessageBox.Show("Input any no");
}
else
{
val = Convert.ToInt32(textBox1.Text);
Thread ot1 = new Thread(new ParameterizedThreadStart(SumData));
ot1.Start(val);
}
}
private static void ReadData(object state)
{
System.Windows.Forms.Application.Run();
}
void setTextboxText(int result)
{
if (this.InvokeRequired)
{
this.Invoke(new IntDelegate(SetTextboxTextSafe), new object[] { result });
}
else
{
SetTextboxTextSafe(result);
}
}
void SetTextboxTextSafe(int result)
{
label1.Text = result.ToString();
}
private static void SumData(object state)
{
int result;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
setTextboxText(result);
}
delegate void IntDelegate(int result);
private void button2_Click(object sender, EventArgs e)
{
Application.Exit();
}
}
}
Why is this error occurring?
An object reference is required for the nonstatic field, method, or property 'WindowsApplication1.Form1.setTextboxText(int)
It looks like you are calling a non static member (a property or method, specifically setTextboxText) from a static method (specifically SumData). You will need to either:
Make the called member static also:
static void setTextboxText(int result)
{
// Write static logic for setTextboxText.
// This may require a static singleton instance of Form1.
}
Create an instance of Form1 within the calling method:
private static void SumData(object state)
{
int result = 0;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
Form1 frm1 = new Form1();
frm1.setTextboxText(result);
}
Passing in an instance of Form1 would be an option also.
Make the calling method a non-static instance method (of Form1):
private void SumData(object state)
{
int result = 0;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
setTextboxText(result);
}
More info about this error can be found on MSDN.
For this case, where you want to get a Control of a Form and are receiving this error, then I have a little bypass for you.
Go to your Program.cs and change
Application.Run(new Form1());
to
public static Form1 form1 = new Form1(); // Place this var out of the constructor
Application.Run(form1);
Now you can access a control with
Program.form1.<Your control>
Also: Don't forget to set your Control-Access-Level to Public.
And yes I know, this answer does not fit to the question caller, but it fits to googlers who have this specific issue with controls.
You start a thread which runs the static method SumData. However, SumData calls SetTextboxText which isn't static. Thus you need an instance of your form to call SetTextboxText.
Your method must be static
static void setTextboxText(int result)
{
if (this.InvokeRequired)
{
this.Invoke(new IntDelegate(SetTextboxTextSafe), new object[] { result });
}
else
{
SetTextboxTextSafe(result);
}
}
Credit to #COOLGAMETUBE for tipping me off to what ended up working for me. His idea was good but I had a problem when Application.SetCompatibleTextRenderingDefault was called after the form was already created. So with a little change, this is working for me:
static class Program
{
public static Form1 form1; // = new Form1(); // Place this var out of the constructor
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(form1 = new Form1());
}
}
I actually got this error because I was checking InnerHtml for some content that was generated dynamically - i.e. a control that is runat=server.
To solve this I had to remove the "static" keyword on my method, and it ran fine.
From my looking you give a null value to a textbox and return in a ToString() as it is a static method. You can replace it with Convert.ToString() that can enable null value.
Make the function static. This must solve your problem.
The essence, and solution, to your problem is this:
using System;
namespace myNameSpace
{
class Program
{
private void method()
{
Console.WriteLine("Hello World!");
}
static void Main(string[] args)
{
method();//<-- Compile Time error because an instantiation of the Program class doesnt exist
Program p = new Program();
p.method();//Now it works. (You could also make method() static to get it to work)
}
}
}
this is basically a follow up to a previous question (Triggering an event in c# from c++ and declaring LPCWSTR). I've revised my code based on the answers and comments I have received and I solved the initial issue, which was passing the event to the GpioSetupInterruptPin from a gpio api. I don't have a lot of documentation on the api but what i'm trying to achieve is: have a form with a white label; after pressing a switch, the label turns yellow.
The problem i'm having now is the event seems to trigger as soon as it's created (the "execute" message is passed to the debug dialog and the label turns yellow) but it doesn't do anything when i toggle the switch. I was told in the last question to use WaitForSingleObject but i'm not really sure where to call it and this article only added to my confusion.
public partial class Form1 : Form
{
// P/Invoke CreateEvent and WaitForSingleObject
private void GPIO_Open() //get handle for gpio
private void GPIO_Output() //output pin declaration
private void button1_Click(object sender, EventArgs e)
{
Interrupt_Setup();
}
private void Interrupt_Setup()
{
hGPIO = GPIOapi.GpioOpenHandle(); //returns a handle to the gpio
GIPO_ON = true;
Debug.WriteLine("Driver open \n" + hGPIO);
GPIO_Output(); //set output pins
GPIO_Interrupt(Trigger); //configure interrupt
}
private void GPIO_Interrupt(string trigger)
{
bool ok;
_Main();
//INTERRUPT DECALRATION
ok = GPIOapi.GpioSetupInterruptPin(hGPIO, port6, 4, GPIOapi.INT_TRIGGER_MODE.TRIGGER_MODE_EDGE,
GPIOapi.INT_TRIGGER_POLARITY.TRIGGER_POL_HIGH_RISING, trigger, true);
Thread waitThread=new Thread(WaitForTrigger);
waitThread.Start();
if (!ok)
Debug.WriteLine("NO interrupt");
else
Debug.WriteLine("Interrupt set for:" + port6 + "04" + " at " + hGPIO);
}
public static string Trigger = "InputProcessUpdateHandler";
public static IntPtr handle = CreateEvent(IntPtr.Zero, false, false, Trigger); //used P/Invoke
private static InputProcessor inputProcessor = null;
public Color[] color =
{
Color.Orchid, Color.DarkOrchid, Color.GreenYellow, Color.CornflowerBlue, Color.SteelBlue,Color.Crimson
};
public int i = 0;
public void WaitForTrigger()
{
while(true)
{try
{
if (WaitForSingleObject(handle, 0xFFFFFFFF) == false)
{
BeginInvoke(((System.Action)(() =>label2.BackColor = color[i])));
i++;
if (i > 4)
i = 0;
}
Thread.Sleep(300);
}
catch (Exception e)
{ Debug.WriteLine("exception: " + e); }}
}
}
private void _Main()
{
inputProcessor = new InputProcessor();
ShowToggle showToggle = new ShowToggle(inputProcessor);
inputProcessor.Process(label1);
}
public class ShowToggle
{
private InputProcessor _inputProcessor = null;
public ShowToggle(InputProcessor inputProcessor)
{
_inputProcessor = inputProcessor;
_inputProcessor.updateHandledBy += InputProcessUpdateHandler;
}
private void InputProcessUpdateHandler(Label label)
{
label.BackColor = Color.Yellow;
Debug.Write("execute");
}
}
public class InputProcessor
{
public delegate void InputProcessUpdateHandler(Label label);
public event InputProcessUpdateHandler updateHandledBy = null;
public void Process(Label label)
{
if (updateHandledBy != null)
updateHandledBy(label);
}
}
If anyone could help me with this, I would be very grateful.
*** I got it working but it looks a right mess. Could anyone help me straighten it out?
You code is really confusing to me. I think what you want is something like this. Bear in mind I'm typing this into the SO text editor, so don't expect it to compile and just work - it's a guide. Consider it a step above pseudocode.
public class DeviceInterrupt
{
IntPtr m_gpio;
string m_eventName;
public event EventHandler OnInterrupt;
public DeviceInterrupt(int port)
{
// get a driver handle
m_gpio = GPIO_Open();
// generate some unique event name
m_eventName = "GPIO_evt_" + port;
// wire up the interrupt
GpioSetupInterruptPin(m_gpio, port, m_eventName, ...);
// start a listener
new Thread(EventListenerProc)
{
IsBackground = true,
Name = "gpio listener"
}
.Start();
}
public void Dispose()
{
// TODO: release the handle
}
private void EventListenerProc()
{
// create the event with the name we sent to the driver
var wh = new WaitHandle(false, m_eventName);
while (true)
{
// wait for it to get set by the driver
if (wh.WaitOne(1000))
{
// we have an interrupt
OnInterrupt.Fire(this, EventArgs.Empty);
}
}
}
}
Usage would then be something like this:
var intr = new DeviceInterrupt(4);
intr.OnInterrupt += MyHandler;
....
void MyHandler(object sender, EventArgs a)
{
Debug.WriteLine("Interrupt occurred!");
}
Note
The Compact Framework doesn't support actual named system events, so the named WaitHandle I use in my code above is not a CF-supplied WaitHandle. Instead I'm using the one from the Smart Device Framework. You could also P/Invoke to CreateEvent and WaitForSingleObject yourself.
I have this code:
private void timer1_Tick(object sender, EventArgs e)
{
#region BaseAddress
Process[] test = Process.GetProcessesByName(process); //Get process handle
if (test.Any())
{
int Base = test[0].MainModule.BaseAddress.ToInt32();
}
#endregion
//lots of other code blocks
}
I now want to take the region 'BaseAddress' out of the timer1_Tick control to make the code more efficient and have it run once at the beginning of the program. The other code in this control makes frequent use of the variable 'Base', what is the best way to make this globally accessible without having to go back through all the instances that use Base and do something like MyGlobals.Base, for example?
Lazy load the address into a static variable. It won't initialize until you use it for the first time, then will remain in memory for the life of the application.
public static MyGlobals
{
private static readonly Lazy<int> _processBase = new Lazy<int>(() => GetProcessBase("MyProcessName"));
// I don't recommend using the word Base, but OK...
public static int Base { get { return _processBase.Value; } }
private static int GetProcessBase(string processName)
{
int b = 0;
Process[] p = Process.GetProcessesByName(processName);
if(p != null && p.Length > 0)
{
b = p[0].MainModule.BaseAddress.ToInt32();
}
return b;
}
}
In some other part of the app...
private void timer1_Tick(object sender, EventArgs e)
{
if(MyGlobals.Base > 0)
{
// TODO: change "Base" to "MyGlobals.Base" in code below or it won't compile...
//lots of other code blocks
}
}
The method I would use in this case would be to create a singleton class ProcessFetcher (for example) with a Base property.
My class would have a fetch() function and isDataPresent property.
You can decide to call fetch manually or put it on the constructor.
Consider:
namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
//int[] val = { 0, 0};
int val;
if (textBox1.Text == "")
{
MessageBox.Show("Input any no");
}
else
{
val = Convert.ToInt32(textBox1.Text);
Thread ot1 = new Thread(new ParameterizedThreadStart(SumData));
ot1.Start(val);
}
}
private static void ReadData(object state)
{
System.Windows.Forms.Application.Run();
}
void setTextboxText(int result)
{
if (this.InvokeRequired)
{
this.Invoke(new IntDelegate(SetTextboxTextSafe), new object[] { result });
}
else
{
SetTextboxTextSafe(result);
}
}
void SetTextboxTextSafe(int result)
{
label1.Text = result.ToString();
}
private static void SumData(object state)
{
int result;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
setTextboxText(result);
}
delegate void IntDelegate(int result);
private void button2_Click(object sender, EventArgs e)
{
Application.Exit();
}
}
}
Why is this error occurring?
An object reference is required for the nonstatic field, method, or property 'WindowsApplication1.Form1.setTextboxText(int)
It looks like you are calling a non static member (a property or method, specifically setTextboxText) from a static method (specifically SumData). You will need to either:
Make the called member static also:
static void setTextboxText(int result)
{
// Write static logic for setTextboxText.
// This may require a static singleton instance of Form1.
}
Create an instance of Form1 within the calling method:
private static void SumData(object state)
{
int result = 0;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
Form1 frm1 = new Form1();
frm1.setTextboxText(result);
}
Passing in an instance of Form1 would be an option also.
Make the calling method a non-static instance method (of Form1):
private void SumData(object state)
{
int result = 0;
//int[] icount = (int[])state;
int icount = (int)state;
for (int i = icount; i > 0; i--)
{
result += i;
System.Threading.Thread.Sleep(1000);
}
setTextboxText(result);
}
More info about this error can be found on MSDN.
For this case, where you want to get a Control of a Form and are receiving this error, then I have a little bypass for you.
Go to your Program.cs and change
Application.Run(new Form1());
to
public static Form1 form1 = new Form1(); // Place this var out of the constructor
Application.Run(form1);
Now you can access a control with
Program.form1.<Your control>
Also: Don't forget to set your Control-Access-Level to Public.
And yes I know, this answer does not fit to the question caller, but it fits to googlers who have this specific issue with controls.
You start a thread which runs the static method SumData. However, SumData calls SetTextboxText which isn't static. Thus you need an instance of your form to call SetTextboxText.
Your method must be static
static void setTextboxText(int result)
{
if (this.InvokeRequired)
{
this.Invoke(new IntDelegate(SetTextboxTextSafe), new object[] { result });
}
else
{
SetTextboxTextSafe(result);
}
}
Credit to #COOLGAMETUBE for tipping me off to what ended up working for me. His idea was good but I had a problem when Application.SetCompatibleTextRenderingDefault was called after the form was already created. So with a little change, this is working for me:
static class Program
{
public static Form1 form1; // = new Form1(); // Place this var out of the constructor
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(form1 = new Form1());
}
}
I actually got this error because I was checking InnerHtml for some content that was generated dynamically - i.e. a control that is runat=server.
To solve this I had to remove the "static" keyword on my method, and it ran fine.
From my looking you give a null value to a textbox and return in a ToString() as it is a static method. You can replace it with Convert.ToString() that can enable null value.
Make the function static. This must solve your problem.
The essence, and solution, to your problem is this:
using System;
namespace myNameSpace
{
class Program
{
private void method()
{
Console.WriteLine("Hello World!");
}
static void Main(string[] args)
{
method();//<-- Compile Time error because an instantiation of the Program class doesnt exist
Program p = new Program();
p.method();//Now it works. (You could also make method() static to get it to work)
}
}
}