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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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(Another garbage sentence was needed to get this post accepted amidst bugs and cache issues, sorry for that)
And the harder half of the job is getting the state back, which requires a cast as I said:
int myState=(int)myControl.Tag;
And no, I don't have a reference about this subject.
Inheriting from a class, or creating a more specialized one, is a fundamental concept in Object-Oriented Programming. There are zillions of articles on the subject, why not try and read Custom Button - Issues with Focus Border, Text Color, etc.[^] (I didn't, it was the first I found using CP search).
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Sorry for the delay. If you want to keep number of clicks inside the button, all you have to do is subclass Button class and add a field with the number of clicks. Then, override the OnClick method to increase the number of clicks by one every time the button is clicked. Don't forget to call the parent OnClick so that the normal button click behavior is executed.
You have an example below.
using System;
using System.Drawing;
using System.Windows.Forms;
class CountClickButton : Button {
int clickCount;
public CountClickButton() {
clickCount = 0;
}
protected override void OnClick(EventArgs e) {
clickCount = clickCount + 1;
base.OnClick(e);
}
public int ClickCount {
get {
return clickCount;
}
}
}
class CountClickForm : Form {
CountClickButton b;
public CountClickForm() {
b = new CountClickButton();
b.Text = "Click me!";
b.Size = b.PreferredSize;
ClientSize = new Size(700, 400);
b.Left = (ClientSize.Width - b.Width) / 2;
b.Top = (ClientSize.Height - b.Height) / 2;
b.Click += new EventHandler(b_clicked);
Controls.Add(b);
Text = "I count clicks!";
}
void b_clicked(object sender, EventArgs e) {
string text = String.Format("Button has been clicked {0} times.", b.ClickCount);
if (b.ClickCount < 1) {
text = "Sorry, I was drunk when programming this. Cheers!!";
}
if (b.ClickCount == 1) {
text = "Button has been clicked once.";
}
if (b.ClickCount == 2) {
text = "Button has been clicked twice.";
}
Text = text;
}
[STAThreadAttribute]
static void Main() {
Application.Run(new CountClickForm());
}
}
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usually in vb.net i do like this,
Dim id As Guid = DirectCast(DirectCast(Me.ABCBindingSource.Current, DataRowView)("IdABC"), Guid)
but in C# is like this,
Guid id = ((DataRowView)this.ABCBindingSource.Current)["IdABC"];
tried a lot of code to convert it to Guid and all fail.
even this way didn't works.
Guid id = Convert.ChangeType(((DataRowView)this.categoryBindingSource.Current)["IdCategory"],Guid);
Edit :
omg randomly write and i got like this,
Guid id = (Guid)((DataRowView)this.categoryBindingSource.Current)["IdCategory"];
real hard to move from vb.net to c#..
modified 23-Jun-12 2:08am.
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Does that mean you found the solution - because the (Guid) option is the one I would have gone for first...
If you solve it yourself, please edit the question and add "[Solved]" to the subject line - that way it's obvious!
Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water
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okay, thank you..
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You're welcome!
Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water
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I have a Listbox that show items from a database. I have a button that I want to use to show details of an item selected. Right now I click the button and a new window opens with all the records in a DataGridview, but it defaults to the top of the list. I want it to go directly to that record when I click the button instead of having to scroll to find it. Could someone point me in the direction I need to go to find the method I need to use. Not asking for a ride, just directions.
My favorite bits make quarters.
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Sorry, the Q&A where I was, was not easily discerned from the C# forum. I reposted the second one because the first one I felt did not have enough info in it. Navigation in some places here can be kind of confusing. It was easier when I first signed up here.
My favorite bits make quarters.
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Hi All,
I`m working on server client application and I would like to send a byte array with a message and bytes.
For example:
in the byteArray i`ll have place for string "Name" , "Message"(will be "Image") , and then the bytes of the image.
When the server will get the bytes I will he the ability to know who send it(His name) and what did he sent in this case image.
Then I will take the last part of the byte[] and will convert the bytes to Image and display it on client winform.
Any one can help here ?
Thanks,
Doron
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If you know the exact length of each text field, this is pretty easy to do.
using System.Text;
string name = Encoding.ASCII.GetString(byteArray, 0, nameFieldLength)
string message = Encoding.ASCII.GetString(byteArray, nameFieldLength, messageFieldLength)
Then getting the image itself depends on whether you're working in WinForms or WPF, but either one lets you load a bitmap image from a byte array.
If you're going to use variable-length fields, then you'll need some kind of delimiter to tell you which bytes to grab, and it gets slightly more complex.
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