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You are asking your questions in the wrong way, mixing up UI elements with HttpHandler logic.
It usually works like this: UI generates an event, in response to which the page issues a request with specific URL that's sent to your HttpHandler, which then writes the response back.
You can find a few article on this forum about use of HttpHandler, I will only add to the list the one that I published: Basic Routing for HttpHandler[^]
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Don't include your email in posts on a public forum. You will get lots of spam. CP users can email you if you have ticked the 'allow private email replies' box, and you don't need to expose your email.
You shouldn't need to mess about with HTTP handlers for this, just use a traditional AJAX request sent to a URL which is handled by the normal ASP.net framework (i.e. something.aspx in the old way, or /Controller/Method in MVC).
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How to override button click event in c#
Thanks & Regards
Thahir
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Sorry?
What do you mean by "override button click event"?
Do you mean add a handler? Or prevent an existing handler from working?
Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water
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prevent an existing handler from working.
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If the app is a .NET WinForms app where you have something that implements a Form or other Container, holding a Button having a Click handler implemented by providing an OnClick() handler, then you should provide your own override OnClick(...) handler and inide it NOT call base.OnClick(). If OTOH the current handler was added using Click+=new EventHandler(myNewClickHandler) then you have to remove that handler, either by removing the code that adds it, or by actually removing it using the -= operator.
See, it would be easier if you stated a more complete and clear question, possibly showing some code.
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I used override keyword, now it is working but triggering twice.
protected virtual void btnDate_Click(object sender, EventArgs e)
{
MessageBox.Show("Base");
}
protected override void btnDate_Click(object sender, EventArgs e)
{
MessageBox.Show("Child");
};
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Disconnect the handler? 
Why would you setup a handler and then not use it?? Granted, I know nothing about your project and or what you're doing.
Another method is to override the OnClick method. The Onxxx methods are where the events are raised from in controls. Create your own button and override the OnClick method with some code that determines in the click event should fire. If it does, just call the base OnClick method.
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Hi all,
Suppose I have a button in a windows form app that when clicked just once causes a text box to display one message, and when clicked twice causes the text box to display a different message. I have tried to use an if statement like the following to record the number of mouse clicks but it's not working.
int clickCount=1;
if (clickCount < 2)
{
txtDisplay.Text = txtDisplay.Text + "Side1";
clickCount++;
}
else
{
txtDisplay.Text = txtDisplay.Text + "Side2";
}
It appears that each time the mouse is clicked, clickCount is set to 1 instead of having the value from the previous click. How do I store a value from the previous click event and use it in the current event? Please point me in the right direction, thanks in advance.
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You need to make clickCount a static variable so it is set to 1 at the beginning of the application.
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Sorry to disagree with you, but this behavior of the static keyword corresponds to C++ and not C#. In fact, if you try to set a local variable ( i.e. defined inside a method ) as static in C#, you will obtain a compiler error.
In my opinion, the best option to have clickCount record the number of clicks is to define it as a member variable and not a local one.
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ignrod wrote: but this behavior of the static keyword corresponds to C++ and not C#.
Sorry to disagree with you but I guess you have not read this[^].
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In fact, I have. If you have a look at the link you just posted, you will see a note in yellow color which says: "The static keyword has more limited uses than in C++. To compare with the C++ keyword, see Static (C++)."
So, if you try the following code, it will not compile in C#
class ClickCount {
static void Main() {
ClickCount click = new ClickCount();
click.IncreaseClickCountByOne();
click.IncreaseClickCountByOne();
click.IncreaseClickCountByOne();
}
void IncreaseClickCountByOne() {
static int clickCount = 1;
clickCount = clickCount + 1;
Console.WriteLine(clickCount);
}
}
Of course, member variables ( fields ) can be static or nonstatic. Any of them will keep their value between method calls.
class ClickCount {
static int clickCount = 1;
static void Main() {
ClickCount click = new ClickCount();
click.IncreaseClickCountByOne();
click.IncreaseClickCountByOne();
click.IncreaseClickCountByOne();
}
void IncreaseClickCountByOne() {
clickCount = clickCount + 1;
Console.WriteLine(clickCount);
}
}
class ClickCount {
int clickCount = 1;
static void Main() {
ClickCount click = new ClickCount();
click.IncreaseClickCountByOne();
click.IncreaseClickCountByOne();
click.IncreaseClickCountByOne();
}
void IncreaseClickCountByOne() {
clickCount = clickCount + 1;
Console.WriteLine(clickCount);
}
}
Both work exactly in the same way.
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Yes I agree, but that is not what I was suggesting.
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Sorry to disagree with you, but Richard is correct. Static variables work in C#.
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Huh? when I try a static inside a method, I do get a compiler error (tried with .NET 2.0)
It is the C++ doc, and not the C# doc (unfortunately), that says: When you declare a variable in a function, the static keyword specifies that the variable retains its state between calls to that function.
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Maybe I was not clear but I was talking about a static class variable.
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As I can't get a local static to work in C# (as C/C++ would allow me to), I figured you meant a class member, but then I am puzzled as to why you want it to be static at all. And that is why I provided another answer to the OP, trying to state things more clearly.
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Luc Pattyn wrote: I am puzzled as to why you want it to be static at all
My C++ brain again ...
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you should kickstart the brain that fits the forum. 
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Even with a kick it's slow to react. 
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Same problem. I should have specified class scope statics.
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Your code seems to suggest that you are maintaining the state of your app in a variable (clickCount) which is declared inside the button Click handler, which means it won't survive the handling of a click, hence it will always restart having the value of 1.
You should move the declaration outside the method, i.e. make it a class member. That way, for each instance of the Form (assuming you might create more than one of them), the button would remember its state.
You do not need the static keyword, unless you want to have all instances of that Form to share their state (which seems unlikely to me).
IMO it is easier and robuster to put the state inside the button itself; there are several ways to achieve this;
- one is to create your own MyButton class, inheriting from Button, and taking care of its peculiarities (IMO it would be overkill here);
- another is to hide the state in the Tag property, which is a field provided but unused by Windows for all WinForms Controls, so it is available for whatever purpose you decide to use it for. Mind you, it is of type object, so you would need some casting. (I prefer this approach).
- and then you could derive the state from existing variables and/or properties; in your example, you could perhaps just check the txtDisplay.Text and when it ends on "Side1" just replace "Side1" by "Side2". (I typically don't do it this way, as it is less robust; e.g. when you change languages, there is more code that needs changing).
modified 23-Jun-12 10:12am.
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Hi Luc, thanks for replying. I have searched for a way to "put the state inside the button itself" like you have suggested but all I've found were maintaining session state for web apps and not windows form apps. I'm also interested in your suggestion to "hide the state in the Tag property" but I can't find an example of how to do that either. Please give me links to articles on how to do those things I've just mention if you can. Thanks again for your help.
modified 24-Jun-12 5:55am.
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What's so hard about it??
SomeButton.Tag = stateValue;
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