Assuming there are buttons with all the letters from the alphabet set as Text.
I want to call a function in these buttons and use this letter as argument.
Can I use the same piece of code for each button in some way?
something like
functionname(this.Text);
Problem is, that "this" referrs to the Form and not to the specific button.
In most event mechanisms you can obtain the source of the event; in classic win forms vents this is typically called "sender". You can cast the sender to what you know it is, or some common base-type. For example:
void SomeEventHandler(object sender, SomeEventArgs e) {
string text = ((Control)sender).Text;
// ...
}
Hence with this a single event-handler can handle all the buttons.
This may vary subtly between infrastructure / tools (WCF, XNA etc) but fundamentally should remain similar.
Try an event handler like this:
protected button1_click(sender as object, e as EventArgs) {
var button1 = (Button) sender;
if (button1.Text == "A") {
//for example
}
}
You will then need to add the event handler, either in "on load" using AddHandler... or if it's an Asp.net page you can use the onClick="button1_click" attribute.
For a more specific answer, I would need some more details.
You could use the same event handler for every button on the form:
private void Form_Load(object sender, System.EventArgs e)
{
foreach (var btn in this.Controls.OfType<Button>())
{
btn.Click += AllButtonClick;
}
}
private void AllButtonClick(Object sender, EventArgs e)
{
Button btn = (Button)sender;
String buttonText = btn.Text;
}
Related
I am trying to make a calculator in C# through code only (Just adding a groupBox and a label in designer).
I have successfully added buttons a coma and a +/- sign.
But now I am running into a problem.
I can assign a function to all of them but
I need to assign a function separately to one of the buttons.
so far I have tried this with one button :
double num = Convert.ToDouble(Answer.Text);
Answer.Text = (-num).ToString();
But since I am working with arrays I have no idea how I can separate one button from another.
Essentially I should be able to do this:
If(Numbers[10].IsPressed)
do this.
but again I don't know the syntaxe's well enough
I dont really know what you want to do... But you might try a 'big' event handler... example:
Button[] buttons;
foreach(var button in buttons)
{
button.Click += MyHandler;
}
// method1
private void MyHandler(object sender, EventArgs e)
{
if(sender == buttons[0])
// Do something...
else if(sender == buttons[1])
// do something else...
else if(sender == buttons[2])
// and so on...
}
// method2
private void MyHandler(object sender, EventArgs e)
{
var button = (Button)sender;
switch(button.Text)
{
case "+":
case "1":
case "2":
// and so on...
}
}
Another good approach is having own handler for every button. Usualy Visual Studio will generate own click handler when you double click button in the designer.
private void ButtonPlus_Click(object sender, EventArgs e)
{
// Do something when "+" pressed
}
private void ButtonMinus_Click(object sender, EventArgs e)
{
// Do something when "-" pressed
}
You can manually add event handlers to the buttons in constructor (in case you used Visual Studio for generating it - Visual Studio will automatically add generated event handler to the button)
this.ButtonPlus.Click += ButtonPlus_Click;
this.ButtonMinus.Click += ButtonMinus_Click;
With approach above you will have own functions for every operations, which can help to maintain your code base little bid easily/faster.
However if you want to use only one event handler for all buttons, then you can use Button.Tag property.
Create method for every operation you have
private void ExecutePlus()
{
// Do something when "+" pressed
}
private void ExecuteMinus()
{
// Do something when "+" pressed
}
Then in constructor save all operations in the .Tag property of correspondent button.
this.ButtonPlus.Tag = ExecutePlus;
this.ButtonMinus.Tag = ExecuteMinus;
// add "general" event handler
var buttons = new[] { this.ButtonPlus, this.ButtonMinus };
foreach(var button in buttons)
{
button.Click += Button_Click;
}
Then create "general" click handler
private void Button_Click(object sender, EventArgs e)
{
var button = (Button)sender;
Action execute = (Action)button.Tag;
execute();
}
You will still have separated method for every operation, but only one event handler for all buttons
I'm a beginner and have an assignment in which I must program the game of NIM. I begin with 15 "tokens" and at each turn a maximum of three can be removed, or "hidden". So far I am hiding these tokens on click by doing the following.
private void button1_Click(object sender, EventArgs e)
{
button1.Visible = false;
}
private void button2_Click(object sender, EventArgs e)
{
button2.Visible = false;
}
I simply copied and pasted that multiple times and changed the button numbers so that my buttons will close on click. This might be obvious, but is there a more efficient way to do this, instead of having 15 button close methods?
You can use the same click event for every single button, and make use of the sender object, casting it to Button:
private void buttonsToClose_Click(object sender, EventArgs e)
{
((Button)sender).Visible = false;
}
Then just add that handler to every single button you want to close itself on click.
Note, though, that this will throw an InvalidCastException if you or anyone else uses this handler on an object that is not a Button, so if you're actually going to use this code I would add some sort of conditional to check the real type of the sender.
Additionally, you could reuse this for any Control object by casting sender to Control instead, given that Button inherits from Control, and all Control objects have the Visible property. Here's an example, with a conditional to guard against an invalid cast:
private void controlToMakeInvisible_Click(object sender, EventArgs e)
{
if (sender.GetType() == typeof(Control))
{
((Control)sender).Visible = false;
}
}
A final note - it seems from your post like you may have a slight misunderstanding about the way events are created and wired in with objects in Windows Forms. If you go into the Designer, add a click event, and see it pop into your Form code as follows:
private void button1_Click(object sender, EventArgs e)
the name of this method has no bearing on its function. The button1 part of button1_Click doesn't actually have any logical linkage with the Button button1 - it's just the default name assigned by the Designer. The actual assignment of the method button1_Click to the Button.Click event is auto-generated into your Form's Designer.cs method.
The point of this is that if you copy and paste button1_Click and change every incidence of button1 with button2, like so:
private void button2_Click(object sender, EventArgs e)
{
button2.Visible = false;
}
it's not going to fire when button2 gets clicked. In actual fact, it's never going to fire at all, because the method hasn't actually been connected to any controls/events.
just call your event in a foreach loop.
private void Form1_Load(object sender, EventArgs e)
{
foreach (var button in Controls.OfType<Button>())
{
button.Click += button_Click;
}
}
void button_Click(object sender, EventArgs e)
{
((Control) sender).Visible = false;
}
if you change:
Controls.OfType<Button>()
to
Controls.OfType<Control>()
it will set visible to false for any Control. so you can control what item you want the event to be raised for easily.
OfType summary: Filters the elements of an IEnumerable based on a specified type.
I want to make a click event for a bunch of buttons. The problem is that I want to use the button's Text, and pass it to a function. Now the click event is passed a object sender. When I tried changing that to Button sender, it gave errors. But I don't know how else I can work with the senders Text.
Here is the normal code, which gave a single error:
private void guess_Click(object sender, EventArgs e)
{
guess(sender.Text);
}
I changed it to this, which gave errors:
private void guess_Click(Button sender, EventArgs e)
{
guess(sender.Text);
}
Question:
How can I work with the Button's Text property within this click event, which is a single click_event for multiple buttons?
Step 1: You need to subscribe to the Button Click event of all your buttons to the same EventHandler. so that button click on all your Buttons will fire the same `Event Handler.
Step 2: You need to cast the object sender into Button and then access its Text property to get the Button Text.
Try This:
button1.Click += new System.EventHandler(MyButtonClick);
button2.Click += new System.EventHandler(MyButtonClick);
button3.Click += new System.EventHandler(MyButtonClick);
private void MyButtonClick(object sender, EventArgs e)
{
Button btnClick = (Button)sender ;
guess(btnClick.Text);
}
Cast sender to type button.
Example:
private void guess_Click(object sender, EventArgs e)
{
guess(((Button)sender).Text);
}
You need to cast the sender object to the Button type and use that:
private void guess_Click(object sender, EventArgs e)
{
Button senderBtn = senderBtn as Button;
if(senderBtn != null)
{
guess(senderBtn.Text);
}
}
I need to dynamically create buttons (one for loop) and add "onClick" and "doubuleClick" events on it.
I did it like this:
Button bt = new Button();
bt.Click += bt_Click;
bt.DoubleClick += bt_DoubleClick;
private void bt_Click(object sender, EventArgs e)
{
label1.Text = this.Text;
}
private void bt_DoubleClick(object sender, EventArgs e)
{
//some code
}
First: My "bt_Click" method gets "main form" text in "label1". In debugger I see that sender is a button. What is wrong with it?
Second: My "bt_DoubleClick" event do not react at all, am I doing something wrong here?
Any help is appreciated.
You should cast sender to Button to get the bt.Text:
Button bt = new Button();
bt.Click += bt_Click;
bt.Text = "click me";
bt.Location = new Point(100,100);
this.Controls.Add(bt);
private void bt_Click(object sender, EventArgs e)
{
label1.Text = (sender as Button).Text;
}
Buttons doesn't react to double click event. You can read it here in detail.
In response to the first question, if I understand you correctly, in this.Text, this refers to the form because the method bt_Click is a member of the Main Form class. I think you might have meant to do:
private void bt_Click(object sender, EventArgs e)
{
label1.Text = (Button)sender.Text;
}
Second: Is this just a case of the bt_Click handler firing twice?
The easiest way to do this it is to use "datagrid".
Datagread has the great support for all events and for organization of items (image, text and so on).
I have made "save" or "open" dialog form to browse content from remote SFTP server, very easy with datagrad, but I had a problem to do it with buttons or labels.
I have a Windows form named Form1 and panel within this form named panel1. I use the panel only to place buttons there so that I can group them and work with them separately from the other buttons in my Form1. For the purpose of my program I need to handle every button click made from the buttons inside panel1. For this purpose I use the same code snippet:
public Form1()
{
InitializeComponent();
// Set a click event handler for the button in the panel
foreach (var button in panel1.Controls.OfType<Button>())
{
button.Click += HandleClick;
}
}
What I need to do is to have a way to identify which button exactly has been clicked. For this purpose I played a little bit with my handler method:
private void HandleClick(object o, EventArgs e)
{
MessageBox.Show("HI" + o.ToString());
}
which gave me some hope because I get this:
It's the second part - Text: button4 which is actually enough information to continue with my work. But I can't find a way to get this piece of information without some complicated string manipulations. So is there a way to get this or other unique information about the button been clicked given the way I have written my code?
private void HandleClick(object sender, EventArgs e)
{
var btn = sender as Button;
if (btn != null)
{
MessageBox.Show(btn.Text);
}
}
One option is to cast the object to a Button, but rather than doing the casting you can change how the event handler is assigned so that you don't need to cast in the first place:
foreach (var button in panel1.Controls.OfType<Button>())
{
button.Click += (_,args)=> HandleClick(button, args);
}
Then just change the signature of HandleClick to:
private void HandleClick(Button button, EventArgs e);
You need to cast sender to the Button class so you can access its properties:
Button b = (Button)sender;
MessageBox.Show(b.Text);