I'm starting to think this is a stupid question, because I cannot find anything related but here goes.
So I've been learning C# and trying to figure out methods, so I created a simple method that increases a variable when used. So then I attached it to a button in Microsoft Visual Forms. However it only seems to increase the value once and then the computer stops executing the method.
Here's My Code
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
int number = 0;
public void button1_Click(object sender, EventArgs e)
{
NumberMethod(number);
}
public int NumberMethod(int number)
{
number++;
label1.Text = number.ToString("Number:#");
return number;
}
}
So again I want it to execute the method and increase the variable every time someone clicks the button.
Try using this keyword:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
int number = 0;
public void button1_Click(object sender, EventArgs e)
{
NumberMethod();
}
public int NumberMethod()
{
this.number++;
label1.Text = this.number.ToString("Number:#");
return this.number;
}
}
Explanation:
When you invoke NumberMethod(number) it passes only the value which is initially zero. And that is incremented by 1 from the function. The important thing is the value of the variable number is not changed yet (it remains zero). The same happens again and again.
In my solution, we are not passing the value, but changing the value of number from the method itself.
Related
This is my first question here and, although it's probably a very nooby one, it's had me stumped for quite a while. I'm using a simplified example to explain.
On a Console Application, I have a public int 'x' set to 0 and a method 'test' which changes it to 1. When 'test' is called in Main, the value of X is now 1 (as expected).
public int x = 0;
public void test()
{
x = 1;
}
static void Main(string[] args)
{
Program program = new Program();
program.test();
Console.WriteLine(program.x);
Console.ReadLine();
}
However (and this is what I don't understand), when using a button_Click event to call the same 'test' method on a Windows Form Application, 'x' remains as 0:
public Form1()
{
InitializeComponent();
}
public int x = 0;
public void test()
{
x = 1;
}
private void button1_Click(object sender, EventArgs e)
{
Form1 form = new Form1();
form.test();
MessageBox.Show("" + x);
}
}
So to summarize, what I am wanting to happen is for 'test' to be called when the button is clicked, changeing the value of 'x' to 1. Can anyone explain why this isn't working?
Thanks!
You've create two separate instances of Form1. Calling the test() method on the second instance is not going to affect the value of x in the first instance.
Change the button click event, so that you're not creating a new Form1.
private void button1_Click(object sender, EventArgs e)
{
test(); // now it'll call test() on the current instance, and modify x as you expect
MessageBox.Show("" + x);
}
Because is happening for the form that you created with Form1 form = new Form1();
Remove that line,call only test() and try again, it should work.
How would I share variables between "Click on a button" functions inside a WinForms application? I tried reading about it, but I'm quite new to this and didn't really get it clear - from what I understand, I have to use the static keyword?
I don't really know how to explain it, so I'll just show some simple code (that has mistakes in it, since I don't know how to make it work):
namespace stackoverflow
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
label1.Text = "Not clicked!";
int number = 0;
}
private void label1_Click(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
label1.Text = "Clicked button 1.";
number = 1;
}
private void button2_Click(object sender, EventArgs e)
{
label1.Text = "Clicked button 2.";
number = 2;
}
}
}
How would I make the number actually update in the whole class...?
They don't have to be static since you're using the same instance of the Form1 class. Since the event handlers are properties of the form and not the buttons, you can use form-level member form all event handlers:
public partial class Form1 : Form
{
private int number = 0; // field at the form level
public Form1()
{
InitializeComponent();
label1.Text = "Not clicked!";
}
private void label1_Click(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
label1.Text = "Clicked button 1.";
number = 1;
}
private void button2_Click(object sender, EventArgs e)
{
label1.Text = "Clicked button 2.";
number = 2;
}
}
It helps when you understand what the accessibility types mean.
When something is declared as static, it means that the variable occupies a single place in memory for the lifetime of the application. Calling or assigning to that variable will only ever affect a single memory location/offset.
Non-Static variables are, as you say, 'members' of an instance of a type.
The difference in how they are accessed is that you would need to prefix the variable with the instance of the class which contains the variable.
theFormInstance.Number = 5;
or
this.Number=5;
Static variables however, are referenced by using the type name.
I like to think of it as 'belonging'
A static variable 'belongs to the type' where a non-static 'belongs to an instance of the type'
Form1.Number= 5;
While yes, you can use Static variables, you shouldn't need to in this particular example because the variable you are attempting to alter resides within the same Form class as the click events.
As long as the variable is declared outside of the click event handlers/methods, but within the enclosing class - then all methods within the Form1 class will have access to the variable.
Note - I suspect that because you were clicking on buttons, you assumed that the buttons wouldn't have visibility to the form class, because they are other controls etc.
The thing to remember is that while the buttons are triggering the event handler 'click' to execute, it is still the Form that is running the code.
Eg:
MessageBox.Show(this.Name);
This will return the Form's name, no matter where you execute it within the Form, whether it be in a buttons click event or in a form load event.
If you wanted to grab the button from inside an event handler, then you could use the 'sender' variable to reference the button.
(You would need to cast it to the proper type though.
Eg
private void button2_Click(object sender, EventArgs e)
{
Button btn = (Button)sender;
label1.Text = "Clicked "+btn.Name;
number = 2;
}
Anyway, know this goes off in a few directions, but hope its informative and gives you an insight into accessibility within forms.
Just remember - Controls live within the Form, so they have equal access to all variables declared within the form - as long as they are inside the form but outside of method bodies.
You have the same instance of the class. There's no need to use static, all you need is a simple field, rather than using a local:
public partial class Form1 : Form
{
int number;
...
}
Put the int number = 0; in the class declaration and not in the constructor. (E.g. put it between the public Form1() and public partial class Form1 { lines)
Basically to regurgitate what everyone else is saying:
Either create a class and work directly from that that contains your properties and fields, pass that between your forms. I wouldn't put a field/property anywhere in your Form.cs except the top, just to keep it clean really. I would check out WPF and the MVVM pattern to be honest, this is where it excels at and it's really the future. I went the route of Winforms/WebForms and now only develop using WPF/MVC and really wish I would have just skipped the other stuff. Just my two cents to be honest.
Initialize the number outside form function like
namespace stackoverflow
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
label1.Text = "Not clicked!";
}
int number = 0;
private void label1_Click(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
label1.Text = "Clicked button 1.";
number = 1;
}
private void button2_Click(object sender, EventArgs e)
{
label1.Text = "Clicked button 2.";
number = 2;
}
}
}
Declare the variable at class level rather than locally.
public partial class Form1 : Form
{
int number = 0;
public Form1()
{
...
I have two classes, Form1.cs and secondclass.cs, I'm trying to do something on secondclass.cs and send the progress to a progress bar on Form1.cs , this is my current code:
Form1.cs
namespace DifferentClasses
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
secondclass.updateBar(20);
}
private void button2_Click(object sender, EventArgs e)
{
this.setBar(20);
}
public void setBar(int percentage)
{
this.progressBar1.Value += percentage;
Console.WriteLine(Convert.ToString(percentage));
}
}
}
secondclass.cs
namespace DifferentClasses
{
class secondclass
{
public static void updateBar(int percentage)
{
var frm = new Form1();
frm.setBar(percentage);
}
}
}
(this was a new project to test what I actually want in my main program)
as you see I have created 2 buttons, the first one runs the command via secondclass.cs
and the second one runs it directly from the same class. Funny enough both don't give errors
and both return the console line, however the first button doesn't actually change the progress bar and I can't figure out why.
The problem is in updateBar you are creating a new Form1 and setting the percentage on that.
The simplest way to solve this is to pass a reference to the current form into updateBar like this:
public static void updateBar(int percentage,Form1 f)
{
f.setBar(percentage);
}
and in the calling code do this:
secondclass.updateBar(20,this);
I'm guess the secondclass will end up running something which may take some time, so you may want to look at the async features in C#
I found a snippet of code from a similar question but it didn't quite fit my implementation, and I couldn't figure out how to adapt it to my game. I have fifteen buttons and I need to be able to count the number of buttons pressed for each turn of a game. I am a very much a beginner with a limited knowledge of programming. I need to be able to count button presses, and then have the method restart at each players turn.
private void label1_MouseClick(object sender, MouseEventArgs e)
{
int count++;
}
I created mouse click event but I get an error when trying to increment my count int.
Use this class, then you can use ButtonEx instead of Button in your designer
public class ButtonEx : Button
{
public int ClickCount { get; private set; }
public ButtonEx()
{
this.Click += (s, e) => { ++this.ClickCount; };
}
public void ResetPressCount()
{
this.ClickCount = 0;
}
}
I see you have used label instead of button in you application
you can just use this for label
public class LabelEx : Label
{
public int ClickCount { get; private set; }
public LabelEx()
{
this.MouseClick += (s, e) => { ++this.ClickCount; };
}
public void ResetPressCount()
{
this.ClickCount = 0;
}
}
Simple fix.//all these inside form class
//declare count as integer, you can also initialize it ( int count=startvalue;)
int count;
//if you want to understand read topic about delegates and events
private void label1_MouseClick(object sender, MouseEventArgs e)
{
++count;
}
//call reset() when you want to reset
private void reset(){
count=0;
}
Also check
stackoverflow: c# Resources, Books
Because int count++ is Invalid Syntax.
The proper way to create an Increment integer value is;
private int count = 0;
private void label1_MouseClick(object sender, MouseEventArgs e)
{
count++;
}
and to reset the integer count you need to make a reset button or include the count = 0; in your desire method.
I've stomped with a problem I've spent some hours trying to solve, with my very limited knowledge.
I have a listview in my form1 called listMachine
And I have a method in form1.cs such as
private void máquinaToolStripMenuItem_Click(object sender, EventArgs e)
{
machinename open = new machinename();
open.Show();
}
machinename.cs is another form, and I use that method to open my other form, with an object called open.
the machinename button is a simple form which just serves as an input receiver, it asks a name, we have to type it into the textbox, press a button and it receives the input.
This is the code that runs when you press the button
public void buttonAceitarnome_Click(object sender, EventArgs e)
{
if (textBoxnomenova.TextLength == 0)
{
toolTipEmptyname.Show("O nome da máquina não pode estar vazio", textBoxnomenova);
}
else
{
Variables.var = textBoxnomenova.Text;
//MessageBox.Show(Variables.var); debug purpose, the messagebox does carry variables.var text
obj.listMachine.Items.Add(Variables.var); //If I change the variables.var to "test" it will NOT add the item.
this.Close();
}
}
Also, I forgot to mention my Variables.cs class, I created it because it was the only way I found to pass variables from a class to another (machinename.cs to form1.cs), but still, the items are not added into the listview.
This is my variables.cs code
public static class Variables
{
public static string var;
}
The comments I added to the code also give you some extra debug info..
I didn't want to ask for online help, but couldn't solve this on my own :(
If I were you, I would first remove the Variables class.
Then, you'r first form/class is called obj.cs, am I right? Or is it form1.cs?
I made it look like this:
public partial class obj : Form
{
public static string text; //This is a variable that can be reached from
public obj()
{
InitializeComponent();
}
private void máquinaToolStripMenuItem_Click(object sender, EventArgs e)
{
machinename open = new machinename();
open.ShowDialog(); //I put ShowDialog instead of Show
addItem(); //This method is called when the showed dialog is closed (machinename.cs)
}
private void addItem()
{
listMachine.Items.Add(text);
}
}
and the machinename.cs class like this:
public partial class machinename : Form
{
public machinename()
{
InitializeComponent();
}
private void buttonAceitarnome_Click(object sender, EventArgs e) //This one can be private
{
if (textBoxnomenova.TextLength == 0)
{
//Something here
}
else
{
obj.text = textBoxnomenova.Text; //Initializing the public static variable
this.Close(); //Closes the form, next step will be to run the method in obj.cs
}
}
}
If I understood your question correctly, you wanted to add an item to the ListView called "listMachine" via a button in the form "machinename.cs". This code will do that. I hope it helps you.
Change the click event from private to protected.
protected void máquinaToolStripMenuItem_Click(object sender, EventArgs e)