Develop Reference

C# Windows forms Calculator - Selecting textbox per click

First of all, I'm german, 2. here is a screenshot of my calculator.. kinda weird but well i know xD
So, I'm looking for a Command:
I got 4 Textboxes, the 1st one(textBox1) for the 1. Number,
the 2. one(textBox2) for the Operator (+-*/),
the 3. one for the 2. Number
and the 4. one for the Result
if i do:
private void button3_Click(object sender, EventArgs e)
{
textBox1.SelectedText += "1";
textBox3.SelectedText += "1";
}
or
private void button3_Click(object sender, EventArgs e)
{
textBox1.Text = textBox1.Text + "1";
textBox3.Text = textBox3.Text + "1";
}
the Number from the button I click on is shown in both textboxes now (1. and 3. one).
But I want that the Number of the button i clicked on is going to be in the Textbox i selected first.
So i first do select the textbox1 or textbox3 with simply clicking in it and then i click on a button(for example 1) and then the number 1 is going to be in the textbox i selected/clicked.

On the _Activate Event for both Textboxes, store which box was activated. Then use that in the _Clicked event:
private TextBox currentTextBox;
// Both textboxes can use this function
private void textbox_Activate(object sender, EventArgs e)
{
this.currentTextBox = (TextBox) sender;
}
private void button3_Click(object sender, EventArgs e)
{
currentTextBox.Text = textBox1.Text + "1";
}

You can have a global variable TextBox textBoxSelected then in a event textBox1_Click and textBox3_Click set the variable. Later in button3_Click choose the textboxselected and add your logic.
Try this:
TextBox textBoxSelected;
private void txtBox1_Click(object sender, EventArgs e)
{
textBoxSelected = textBox1;
}
private void txtBox3_Click(object sender, EventArgs e)
{
textBoxSelected = textBox3;
}
private void button3_Click(object sender, EventArgs e)
{
textBoxSelected.Text += "1";
}

I can't make much sense of your question, but I have noticed an issue in your logic.
C# will be adding them as strings, which results in concatenation.
Convert the values to integers first and it will add correctly.
textBox1.Text = int.Parse(textBox1.Text) + 1;
As for you actual question, if you want to have a way of "remembering" what text box you clicked, add an event to the Click event to store the text box control that you have selected in a variable, and then use that in your logic.

So here are some recos:
1/ Naming convention: Use clear names that refer to the button function or the textbox content. Say for example: TextboxLeftOperand, ButtonN1, TextboxOperator, ...
2/ Use a new variable called SelectedTextbox
var SelectedTextbox = new Textbox();
3/ Add to the click event of both textboxes an assignment of the SelectedTextbox.
For the left textbox:
SelectedTextbox = TextboxLeftOperand // textbox1 in your case
And for the right textbox
SelectedTextbox = TextboxRightOperand // textbox1 in your case
4. Now all you have is work with your new variable.

Edit Items in a ListBox

I am creating a program using WinForms so users can input info into textboxes on one form which then are saved into a Listbox on another form. I would like to be able to edit the items saved in the listbox by opening the original form on a button click. Really struggling with it as I can't think of the code and I can't seem to find a solution.
My Code:
private void btnAdd_Click(object sender, EventArgs e)
{
RoomDisplayForm newRoomDisplayForm = new RoomDisplayForm();
newRoomDisplayForm.ShowDialog();
if(newRoomDisplayForm.DialogResult == DialogResult.OK)
{
listBoxRooms.Items.Add(newRoomDisplayForm.value);
}
newRoomDisplayForm.Close();
}
private void btnRemove_Click(object sender, EventArgs e)
{
this.listBoxRooms.Items.RemoveAt(this.listBoxRooms.SelectedIndex);
}
private void btnEdit_Click(object sender, EventArgs e)
{
}
So i've got a Add and Remove button which work perfectly just need a solution to the edit button.
Thanks in advance

I'm guessing newRoomDisplayForm.value is a property or a public member inside the form. You just need to do something like this:
private void btnEdit_Click(object sender, EventArgs e)
{
if(listBoxRooms.SelectedIndex < 0) return;
var tmpValue = listBoxRooms.Items[listBoxRooms.SelectedIndex].ToString();
RoomDisplayForm newRoomDisplayForm = new RoomDisplayForm();
newRoomDisplayForm.value = tmpValue;
newRoomDisplayForm.ShowDialog();
//TODO: inside "newRoomDisplayForm" set the value to the textbox
// ie.: myValueTextBox.Text = this.value;
if(newRoomDisplayForm.DialogResult == DialogResult.OK)
{
// replace the selected item with the new value
listBoxRooms.Items[listBoxRooms.SelectedIndex] = newRoomDisplayForm.value;
}
}
Hope it helps!

You can simply remove the listitem in that specific position, create a new item and add it again. it's kind of replacement.

How to run a diffrent method each time a new comboboxItem has been selected

Hi there just building a small conversion calculator and Im adding a combo box to it so its not as cluttered and easy to manage. I wont to add a few options to my combo box so that the user has different options to choose from. However I'am going to build a small class with the conversion calculations so that when a different option is selected within the combo box the correct method will be called. I will add a code snippet to show use were i'am at. I was just using the message box just so i know that it was working. Any code snippets would be great.
private void comboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ComboBoxItem kilo = ((sender as ComboBox).SelectedItem as ComboBoxItem);
}
private double workOutKilo()
{
double result = 2;
return result;
}

Assign each ComboBoxItem's Tag control a function, within the SelectionChanged event, call the function.

Yeah if you use a switch than it might be easy to choose combined by the code you already have.
I would suggest something like this:
private void comboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ComboBoxItem kilo = ((sender as ComboBox).SelectedItem as ComboBoxItem);
switch (kilo.ToString())
{
case "Kilo":
//Method();
break;
//...
}
}
I guess this would do the job:
private void comboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ComboBox kilo = (sender as ComboBox);
int index = kilo.SelectedIndex;
switch (kilo.ToString())
{
case "0":
//Method();
break;
//...
}
}

Using a generic clear textbox method on event

I've got a program with a lot of text boxes that I've got text in that I want to be cleared on _click and then reset to default if nothing is entered and the user clicks away.
The way I was going to do it is clearly inefficient, having to name the text box each time and I'd like to know how I could go about streamlining it.
this is what I've got at the minute, and I'd have to change the txtUserName for the text box field name each time
private void txtUserName_Click(object sender, EventArgs e)
{
txtUserName.Text = ""
txtUserName.ForeColor = Color.Black;
}
is there a way I can do essentially
private void txtAnyTextBox_Click(object sender, EventArgs e)
{
string caller = //Get this textbox name
this.ClearBoxes(caller)
}
void ClearBoxes(string Caller)
{
Caller.txt.Text = "";
//..... and so on
}

Yes, you can try this (though it's not generic but there is no need for generics in this case):
private void txtAnyTextBox_Click(object sender, EventArgs e)
{
TextBox tb = sender as TextBox;
if(tb != null) tb.Text = "";
}
And you can attach this method to all your textBoxes Click event.
textBox1.Click += txtAnyTextBox_Click;
textBox2.Click += txtAnyTextBox_Click;
I don't think this is gonna work:
void ClearBoxes(string Caller)
{
Caller.txt.Text = "";
//..... and so on
}
If you want to use ClearBoxes method you should pass it your TextBox element.But there is no need for this,you can directly clear your textBox as shown above code.
Also if you want to clear all TextBoxes in the same time,for example one button click you can use this:
private void button1_Click(object sender, EventArgs e)
{
foreach (var tBox in this.Controls.OfType<TextBox>())
{
tBox.Text = "";
}
}

You can use the sender argument for that.
private void txtAnyTextBox_Click(object sender, EventArgs e)
{
var textbox = sender as TextBox;
this.ClearTextbox(textbox)
}
private void ClearTextbox(TextBox textbox)
{
textbox.Text = "";
//...
}

You can get name of textbox from sender of event:
private void txtAnyTextBox_Click(object sender, EventArgs e)
{
TextBox textBox = (TextBox)sender;
string caller = textBox.Name;
this.ClearBoxes(caller); // call your custom method
}
If you want to simply clear textbox text, then you don't need to get its name - you can use it's Clear() method:
private void txtAnyTextBox_Click(object sender, EventArgs e)
{
TextBox textBox = (TextBox)sender;
textBox.Clear();
}
Also you can consider creation of custom textbox, which will have some default value and will resent itself to default when clicked:
public class CustomTextBox : TextBox
{
public string DefaultText { get; set; }
protected override void OnClick(EventArgs e)
{
base.OnClick(e);
Text = DefaultText;
}
}
Use custom textboxes instead of default textboxes, and provide DefaultText value for each custom textbox which should reset itself to something more meaningful than empty string (you can use Properties window for that).

This would be quite nasty - as you'd cause a page reload every time someone clicked in the text box.
A far simpler way would be to do it in javascript.
just add a function to clear the text box, and then maybe use a css selector to enable the function for every text box you want to use it in.
e.g.
<input type="text" class="clearme" />
$(".clearme").click(function() {
$(this).val('');
});
this will do it all client side without causing any post backs.

selected item change ComboBox

Is there any way to prevent changing the selected item in a ComboBox only if for certain conditions? I want to allow update the selected item's displayValue in the ComboBox. But I don't want user to change the selected item when it's being updated. This is a windows application.

Inside your class:
private int _selectedIndex = 0;
Inside your form load method:
comboBox1.Enter += new EventHandler(comboBox1_Enter);
comboBox1.SelectedIndexChanged += new EventHandler(comboBox1_SelectedIndexChanged);
Then the rest of the code:
protected void comboBox1_SelectedIndexChanged(object sender, EventArgs e) {
if (true) { // Add your validation or certain condition here.
(sender as ComboBox).SelectedIndex = _selectedIndex;
}
}
protected void comboBox1_Enter(object sender, EventArgs e) {
_selectedIndex = (sender as ComboBox).SelectedIndex;
}

Try setting set the Enabled property to false. (Or some third-party toolkits like Telerik have a ComboBox with a ReadOnly property.)