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Hi All,
I would like to assign a value to a variable in the Default.aspx.cs section of my code. This value will never change. To prevent having to capture this value throughout the code I want this variable to be accessable throughout the Web Application.
The code looks like this:
public partial Class _Default : System.Web.UI.Page
{
public static int timeout;
protected void Page_Load(object sender, EventArgs e)
{
timeout = toVal;
}
}
One of the classes I want to access the static "timeout" variable:
public partial class FormPage : System.Web.UI.Page
{
protected void Page_PreInit(object sender, EventArgs e)
{
}
}
I had another idea to make a seperate class file out of the code that gets the timeout value from the web.config file. Each time the timeout value is needed call the class and return the timeout. I just feel this would be a waste being that the timeout value will always be the same.
Any help would be really appreciated.
I'm also open to suggestions.
Thank you
modified on Saturday, February 12, 2011 10:51 PM
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Put it in the web.config file or in a session variable.
Static variables are for the life of the class, not globally applied - they will be removed when the instance of the application terminates.
When does the app terminate? For ASP.NET, it terminates when the page load is finished.
I.e. The page request arrives at the server. The app is started, returns the page and is terminated. Any postback, or new page request starts a new instance of the app.
Putting it in a static variable won't work: the static variable would have to be set up anew every time the page is loaded!
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
Digital man: "You are, in short, an idiot with the IQ of an ant and the intellectual capacity of a hose pipe."
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Thank you for your reply.
The timeout is stored in the web.config file, this is where the value is being retrieved from. I need to use this value in my code on multiple pages within the web application.
I am trying to add the value to a session variable within the default.aspx.cs file and then trying to retrieve it from the session variable in another but keep getting the error:
"Object reference not set to an instance of an object."
This indicates to me that the session variable is null, but how can this be when I previously populated it in the default page?
Here is some basic code I put together to make it simpler for testing:
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Session.Add("Test", "Testing session pass");
}
}
public partial class FormPage : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Response.Write(Session["Test"].ToString());
}
}
Do you know what the problem is?
Thank you
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I just tried it locally to be on the safe side, and the only way I could duplicate your problem was by closing the browser and starting a new run, but going directly to a page rather than via the default page. Are you sure you loaded the default page first?
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
Digital man: "You are, in short, an idiot with the IQ of an ant and the intellectual capacity of a hose pipe."
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Thank you. That was the problem, I wasn't running the code from the default.aspx file when testing it out of VS.
Thank you for taking the time to help me out with this. I appreciate it.
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I understand that you don't want to "capture" this value, but isn't this an application setting? If so, add it to the web.config and access it using
ConfigurationManager.AppSettings["MySettingName"]
If it's a per-user setting, then put it into session (which is per-user) and access using
Session["MySettingName"] .....App settings and Session are provided for precisely this kind of thing, so it seems a little redundant to "re-invent the wheel" to store it in another way....
Admittedly, both AppSettings and Session (and Application state for that matter) are dictionaries, so there is a small overhead in the lookups.
C# has already designed away most of the tedium of C++.
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Hi Richard,
Thank you for your reply. The timeout value is stored in the web.config file and after reviving OrigionalGriff's post I went and stored the value, taken from the web.config file and stored it in a session variable.
It appears to be the same solution you propose, which I'm happy to hear as it seems to be the best way to go about it.
Thank you again,
Mel
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Hallo everyone,
I want to make a Simple calculator, as an exercise to get familiar with GUI and C#
I can easily drag 10 buttons, name them btn1, btn2... btn0 and then create the appropriate functions like
private void btn1_Click(object sender, EventArgs e)
and let a member variable have the appropriate value.
But...
isn't there a better way to deal with that? Something like having an array[9], where every field is a button, or sort of it?
I find it ugly and really annoying having 10 functions who do quite the same thing.
Thanks...
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several Controls can share some handler, and Controls have a nice Tag property where you can store whatever you like. So it could be:
AnyDigitButton_Clicked(object sender, EventArgs e) {
Button btn=sender as Button;
number=10*number+(int)btn.Tag;
}
PS: there are lots of articles on calculators around, search CodeProject or Google, and see how they do it.
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
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Thanks for replying.
And how do you link all buttons in a handler? Maybe by putting them inside a groupBox? I tried it so but didn't work. Where does the Method 'AnyDigitButton_Clicked' come from?
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You add a handler to each of the buttons click event, but that handler can be created from the same function. That's it.
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The details depend on the IDE you use. How do you usually tell your app to execute some event handler when some event occurs? you normally can choose the handler's name, choosing a pre-existing one should also be possible.
nstk wrote: Maybe by putting them inside a groupBox?
Nope. GroupBoxes do have their use, especially with RadioButtons, here they most likely don't.
nstk wrote: Where does the Method 'AnyDigitButton_Clicked' come from?
I wrote it; it should show you all it takes is just a few lines of code.
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
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I did the above by adding the 'AnyDigitButton_Clicked' as a handler to the Click Event, but I get the following error:
When casting from a number, the value must be a number less than infinity
A declaration of number as
int number = 0;
inside or outside the function didn't change anything...
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I think I found the solution, being
number = Convert.ToInt32(btn.Tag);
modified on Monday, February 14, 2011 10:08 AM
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If you're using Visual Studio, select the button then in the Properties window click the events icon.
In the dropdown next to the event (Click in this case) you can select any method with the correct signature. Selecting the same method for all button's click event will result in the same handler being called.
To get the value, as Luc said you can use the Tag property - although I would be tempted to add a more suitable property such as Value which would hold an int... something like this:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows.Forms;
public class CalculatorDigitButton : Button
{
public const int MaxValue = 9;
public const int MinValue = 0;
public CalculatorDigitButton()
{
base.Text = "0";
}
private int value;
[Browsable(false)]
public new string Text
{
get { return base.Text; }
set { }
}
public int Value
{
get { return value; }
set
{
if (value < MinValue || value > MaxValue)
throw new ArgumentOutOfRangeException(
"value",
string.Format("Value must be between {0} and {1}",
MinValue, MaxValue));
this.value = value;
base.Text = value.ToString();
}
}
}
public enum CalculatorFunction
{
Add,
Subtract,
Multiply,
Divide
}
public class CalculatorFunctionButton : Button
{
private static readonly List<string> FunctionText = new List<string>(4){
"+", "-", "*", "/" };
private CalculatorFunction function;
public CalculatorFunctionButton()
{
base.Text = FunctionText[0];
}
public CalculatorFunction Function
{
get { return function; }
set
{
if (!Enum.IsDefined(typeof(CalculatorFunction), value))
throw new ArgumentException(
"Function must be a defined value", "Function");
function = value;
base.Text = FunctionText[(int)function];
}
}
[Browsable(false)]
public new string Text
{
get { return base.Text; }
set { }
}
}
Your event handlers for these may look something like this:
private void CalculatorDigitButtonClick(object sender, EventArgs e)
{
CalculatorDigitButton calculatorDigitButton = sender as CalculatorDigitButton;
if (calculatorDigitButton != null)
{
}
}
private void CalculatorFunctionButtonClick(object sender, EventArgs e)
{
CalculatorFunctionButton calculatorFunctionButton = sender as CalculatorFunctionButton;
if (calculatorFunctionButton != null)
{
}
}
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That's a lot of code to avoid an (int) cast, as that is what the specialized button class is basically doing.
And I just realized, the digit buttons probably have a simple numeric Text property already, so maybe int.Parse(btn.Text) is the better approach. Keep in mind it will execute less than once per second as it is an input part of the GUI.
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
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You're right of course, but I always try to take the approach, if it's a value it should be stored as a value. If I want to display a string representation, then I do it by calling ToString or whatever on the value.
Using the Text property as the value by calling Parse would just bug me!
Using Tag would be preferable to that as it's just simple boxing/unboxing, but when subclassing is so easy and the auto Text mechanism (plus any other functionality required) can then be built in, that's the way I would go.
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I'm a bit concerned that you won't stand a chance against Asian competition if you need specialized buttons for a simple calculator; it sounds all too expensive. There is a balance to strike between design principles and economic considerations.
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
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And I just realized, the digit buttons probably have a simple numeric Text property already, so maybe int.Parse(btn.Text) is the better approach. Keep in mind it will execute less than once per second as it is an input part of the GUI.
Yes it is. I tried it and it works perfectly.
Thank you all for the great help!
modified on Monday, February 14, 2011 4:49 PM
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Personally, I wouldn't bother with the (previously suggested) Tag property...the first handler parameter is sender - which is the control that the event originated from...no need for a tag when you already have sufficient info in there to determine which one was clicked.
C# has already designed away most of the tedium of C++.
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I am working in c#. I want to change the colour of button by applying function of timer but is giving error.Can any one solve this problem?? Here is the code
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
System.Timers.Timer greentimer;
System.Timers.Timer redtimer;
public Form1()
{
InitializeComponent();
greentimer = System.Timers.Timer(3000);
greentimer.Elapsed += new System.Timers.ElapsedEventHandler(greenTimer_Elapsed);
greentimer.Start();
redtimer = System.Timers.Timer(3000);
redtimer.Elapsed += new System.Timers.ElapsedEventHandler(redTimer_Elapsed);
redtimer.Start();
}
void redTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
Application.Exit();
}
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
}
}
Error:
Error 1 Program 'C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\obj\Debug\WindowsApplication1.exe' has more than one entry point defined: 'WindowsApplication1.Form1.Main()' C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 40 21 WindowsApplication1
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Usually when you create a new WinForm project the code to instantiate the form will be placed in a main method in a class called Program.cs. Now you have a second entry point (Main method) in your executable. I don't think this has to be a problem as long as you specify in your project properties file which ojbect should provide the entry point.
Modified:
On the project properties dialog change to the application tab and set "Start Object" property to the according object. In your case if you want to use the Main method of your form then choose the Form1 object. As a standard this is set to "Not Set" and if there's more that one entry point the copmiler complains as it is unable to resolve this on its own. Using the command line compiler your can use the /main flag to specify which object is supposed to be the "Start Object".
End Modification
Cheers!
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Thanks but After setting the properties tab it is still giving the following errors:
here is the code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
System.Timers.Timer greentimer;
System.Timers.Timer redtimer;
public Form1()
{
InitializeComponent();
greentimer = System.Timers.Timer(3000);
greentimer.Elapsed += new System.Timers.ElapsedEventHandler(greenTimer_Elapsed);
greentimer.Start();
redtimer = System.Timers.Timer(3000);
redtimer.Elapsed += new System.Timers.ElapsedEventHandler(redTimer_Elapsed);
redtimer.Start();
}
void redTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
button1.Invoke(new Action(() => button1.BackColor=Color.Green));
}
private void button1_Click(object sender, EventArgs e)
{
Application.Exit();
}
[STAThread]
static void Main()
{
Application.Run( Form1);
}
}
}
Errors:
Error 1 Invalid expression term ')' C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 30 41 WindowsApplication1
Error 2 Invalid expression term '>' C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 30 44 WindowsApplication1
Error 3 ) expected C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 30 46 WindowsApplication1
Error 4 ; expected C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 30 75 WindowsApplication1
Error 5 Invalid expression term ')' C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 30 75 WindowsApplication1
Error 8 'System.Timers.Timer' is a 'type', which is not valid in the given context C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 19 40 WindowsApplication1
Error 9 The name 'greenTimer_Elapsed' does not exist in the current context C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 20 73 WindowsApplication1
Error 10 'System.Timers.Timer' is a 'type', which is not valid in the given context C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 23 38 WindowsApplication1
Error 11 'WindowsApplication1.Form1' is a 'type' but is used like a 'variable' C:\Documents and Settings\XPPRESP3\Local Settings\Application Data\Temporary Projects\WindowsApplication1\Form1.cs 42 30 WindowsApplication1
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There are a few problems here:
First, the one you are telling us about: Remove the function at the bottom of your class.
There is already a Main function defined in Program.cs - leave it there and get rid of the one you added.
Secondly, you need a new keyword or two:
greentimer = new System.Timers.Timer(3000);
...
redtimer = new System.Timers.Timer(3000);
I would also change the intervals so they weren't the same: otherwise you won't see one colour at all! Try 3000 and 5000 instead.
And just to be picky, you don't need the invoke, but you do need another close parenthesis...
Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together.
Digital man: "You are, in short, an idiot with the IQ of an ant and the intellectual capacity of a hose pipe."
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Thanks but after removing the main function it is still giving me the following errors:
Here is the code
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
System.Timers.Timer greentimer;
System.Timers.Timer redtimer;
public Form1()
{
InitializeComponent();
greentimer = System.Timers.Timer(3000);
greentimer.Elapsed += new System.Timers.ElapsedEventHandler(greenTimer_Elapsed);
greentimer.Start();
redtimer = System.Timers.Timer(3000);
redtimer.Elapsed += new System.Timers.ElapsedEventHandler(redTimer_Elapsed);
redtimer.Start();
}
void redTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
button1.Invoke(new Action(() =&gt; button1.BackColor=Color.Green));
}
private void button1_Click(object sender, EventArgs e)
{
Application.Exit();
}
}
}
Errors:
Error 1 Invalid expression term ')' C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 30 41 WindowsApplication2
Error 2 Invalid expression term '>' C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 30 44 WindowsApplication2
Error 3 ) expected C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 30 46 WindowsApplication2
Error 4 ; expected C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 30 75 WindowsApplication2
Error 5 Invalid expression term ')' C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 30 75 WindowsApplication2
Error 6 ; expected C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 30 76 WindowsApplication2
Error 8 'System.Timers.Timer' is a 'type', which is not valid in the given context C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 19 40 WindowsApplication2
Error 9 The name 'greenTimer_Elapsed' does not exist in the current context C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 20 73 WindowsApplication2
Error 10 'System.Timers.Timer' is a 'type', which is not valid in the given context C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 23 38 WindowsApplication2
Error 11 'WindowsApplication1.Form1' is a 'type' but is used like a 'variable' C:\Documents and Settings\XPPRESP3\My Documents\Visual Studio 2005\Projects\WindowsApplication2\WindowsApplication2\Form1.cs 42 30 WindowsApplication2
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