Develop Reference

How to Hide and Show a button with if statements c#

I am trying to make a button visible = false if a quantity in a text box is less than or equal to 0. The problem I am having is that you have to click the button in order to activate the function.
Here is my code so far
int quantity = int.Parse(textBox33.Text);
if (quantity <= 0)
button13.Visible = false;
if (quantity > 0)
button13.Visible = true;
do I have to disable the visibility of the text box beforehand?

Simply go to the form editor and double click on the textbox. In the code presented to you after double clicking add your code or double click on the form itself if you want the code to be executed whenever the form is loaded.

At first you should encapsulate the code to update the button in a specific method:
private void UpdateButton13()
{
button13.Visible = quantity > 0; // no need for if/else
}
Then you can call this from every event after which the button should be updated. From your comments it seems you want to update that button
at Form load and
when the text in textBox33 has been changed.
So for example:
public class YourForm : Form
{
public YourForm()
{
InitializeComponents();
// register event handlers:
Load += YourForm_Load;
textBox33.TextChanged += textBox33_TextChanged;
}
private void YourForm_Load(object sender, EventArgs e)
{
UpdateButton13();
}
private void textBox33_TextChanged(object sender, EventArgs e)
{
UpdateButton13();
}
private void UpdateButton13()
{
button13.Visible = quantity > 0; // no need for if/else
}
}
Of course you can also create and register the event handlers in the designer window, without having to write the code in the constructor yourself.
The code above may now seem a little redundant (same code in two methods and a one-line method). But I assume that you want to do further things on loading the form and on changing text, and maybe you want to call UpdateButton13 from other parts of your code, too. So encapsulating here is good style (imho) to avoid problems for further development.

go to textbox events and insert the code to textChanged event.
but for better than that you can do digit validation event
private void textBox33_KeyPress(object sender, KeyPressEventArgs e)
{
if (!System.Text.RegularExpressions.Regex.IsMatch(e.KeyChar.ToString(), "[1-9]"))
{
e.Handled = true;
}
}
in that case order can be only positive number

How to run code when hitting enter in a c# text box

I'm using web forms
Right now my code runs when I leave the text box and the text has changed. I am running into issues. If I change the text but hit a button instead of enter, it resets via code. I need to be able to change the text and click a button which wont yet do anything, or change the text and hit enter which will trigger code.
thanks for the help
This is text changed event for the text box with notations of what im needing to do. really what I think I need is an event for clicking enter, not changing text
protected void txtboxPlate_TextChanged(object sender, EventArgs e)
{
if (txtboxPlate.Text == "plate number")
{
//will check database for "plate number" and do stuff on enter.
}
else
{
resetforms();// on enter
}
else
{
the text has changed by user, but has clicked a button and needs nothing to happen because of this text change
}
}

You need to implement a method for the KeyDown event of your textbox.
private void txtboxPlate_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter) {
//Code
}
}

Keydown is a client-side event, as far as I know you're more than likely going to have to use JavaScript/Jquery.
Refer to the following link:
Textbox Keydown Event
I would of used a comment but... rep issues :/
edit:
To anyone that hasn't realised yet, the question changed to webforms not winforms
Alternative:
Use a button.
You could place a button next to the textfield, it's simple and not a lot of work goes into it. You can set the TabIndex of the textbox to 1 and the TabIndex of the button to 2 so when you hit TAB it will focus the textbox and if pressed again it will focus the button. You could also look into adding the button to the textbox for design purposes.
edit: You also need to think about post back, when you hit a button the page get's post back meaning values are lost, to persist the data within the field you would have to use view state, session variables or a hidden field. For simplicity I'd set the value of the text box to a hidden field and then simply re-apply the value on page_load. If the value needs to persist across multiple postbacks/accessed from other pages use session variables.
So as a code example:
Remove the Text_changed event entirely.
protected void btnDoStuff(object sender, EventArgs e)
{
if(txtPlateNumber.Text == "Plate Number")
{
//Do stuff
}
else
{
//Do other stuff
}
}
-
If you notice the value disappearing after the post back do something like:
protected void btnDoStuff(object sender, EventArgs e)
{
if(txtPlateNumber.Text == "Plate Number")
{
//Do stuff
myHiddenField.Value == txtPlateNumber.Text;
}
else
{
//Do other stuff
}
}
then reset the value on page_load.

If this is winform and you still want to use textchanged you can try catching your code first for example:
protected void txtboxPlate_TextChanged(object sender, EventArgs e)
{
//Catching code
if (txtboxPlate.Text != "")
{
if (txtboxPlate.Text == "plate number")
{
//will check database for "plate number" and do stuff on enter.
}
else
{
resetforms();// on enter
}
}
else
{
the text has changed by user, but has clicked a button and needs nothing to happen because of this text change
}
cause what textchanged is doing is unless txtboxPlate.Text equels "plate number" it will always do the else statement. Correct me if i'm wrong though but i had the same problem before which almost made me go insane.
Or try above 1 upvote code:
protected void txtboxPlate_TextChanged(object sender, EventArgs e)
{
//Event only happens if you press enter
if (e.KeyCode == Keys.Enter)
{
if (txtboxPlate.Text == "plate number")
{
//will check database for "plate number" and do stuff on enter.
}
else
{
resetforms();// on enter
}
}
else
{
the text has changed by user, but has clicked a button and needs nothing to happen because of this text change
}
}

Check whether datagridview had been edited

My C# winform has a datagridview and when I clicked update button, what code should I put to check whether any cells had been edited?
I just need to have a true or false.
Thanks.
===========================================================================
My existing codes:
#region Edit Records
private void InProSysAdministrationEventsUpdateButton_Click(object sender, EventArgs e)
{
if (MessageBox.Show("Please Click Ok to Edit the Events", "Confirmation", MessageBoxButtons.OKCancel) == DialogResult.OK)
{
ManipulateData.UpdateData(connectionString, tblconn, tblscmd, tbldataadaptor, tbldatatable, cmbuilder, "usp_readallevents", readalleventsdataGridView);
}
}
#endregion
I need to do the following:
1) user click on edit
2) system check whether any cell had been edited
3) if no cell edited, it will messagebox.show("No Changes Done.")
4) else, it will update the database.

Have you taken a look at the DataGridView.CellValueChanged Event? MSDN
Would be fairly simple to just write a handler for this and set a flag, or perform whatever action you want.
An example of how you might go about performing this would be:
protected override void OnLoad(EventArgs e)
{
myDataGridView.CellValueChanged += new DataGridViewCellEventHandler(
myDataGridView_CellValueChanged);
}
private void myDataGridView_CellValueChanged(
object sender, DataGridViewCellEventArgs e)
{
//some very crude examples of actions you might want to perform when the event handler is triggered.
myObject.update();
//or something else like
myObject.isUpdatable = true;
}
With regards to point number 3, a msgbox is probably not the best way to inform a user of a non-critical event. It is likely that they are already going to know that they haven't entered any information, and you can provide this feedback less anoyying ways by perhaps flagging required cell, or whatever. Food for thought.
In the future, I'd recommend searching MSDN for the class you are working with, and searching for the type of event, method, or property you are looking for, and see if anything matches. There are plenty of useful examples available as well.

int x=0;
private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
x = 1;
}
if(x==1) //this means that gridView has been updated

How can I keep multiple controls in focus?

I have a tree view on the left side. Selecting a node displays relevant information in a form on the right side.
Would I be able to keep the tree and any one control (textbox, combobox, checkbox) on the right in focus at the same time? This will enable a user to select a field, make a change, select another node, and without having to go back and select the same field again, just type and change the value of the same field.
Thanx.
EDIT
I suppose one could implement such behaviour manually:
private Control __cFocus;
private void {anyControl}_Focus(object sender, EventArgs e)
{
__cFocus = (Control)sender;
}
private void treeView1_AfterSelect(object sender, EventArgs e)
{
__cFocus.Focus();
}
I was just wondering if there exists an automatic / more elegant solution
EDIT 2
Ok, so it seems I'll have to implement it manually. Manual implementation it is then. However, now there seem to be another problem; not sure if I should ask this as a separate question.
When selecting a node the textbox gains focus as intended, but only when using the keyboard. It doesn't work when selecting a node with the mouse. First I thought that it might be a mouse event that's interfering, but stepping revealed that the MouseUp event fired first and then the AfterSelect event which sets the focus, so I don't think it's interfering. The textbox's Enter event is also fired, but for some reason it loses focus again to the tree.
Thanx

no, you cannot keep two controls in focus at the same time. But what you can do is set the focus to the target control in the treeview AfterSelect event
private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
{
textBox1.Focus();
textBox1.SelectAll();
}
then in your textbox leave, save the changes, like so:
private void textBox1_Leave(object sender, EventArgs e)
{
//save changes here
}
this way, everytime you select an item in the treeview, check your textbox for change and save as needed, then you will refocus on the textbox for your next edit

There only can be one element having the focus!
But I have an idea for you that might solve your problem. Assuming you have a window with a TreeView and a TextBox. Set the HideSelection property of the TreeView to false and subscribe the AfterSelect event (like edeperson already answered) like this:
private void OnTreeViewAfterSelect(object sender, TreeViewEventArgs e)
{
textBox1.Text = e.Node.Text;
textBox1.Focus();
}
Then subscribe the KeyDown event of the TextBox and do following in the event method:
private void OnTextBoxKeyDown(object sender, KeyEventArgs e)
{
if ((e.KeyCode == Keys.Up) || (e.KeyCode == Keys.Down))
{
treeView1.Focus();
SendKeys.Send(e.KeyCode == Keys.Up ? "{UP}" : "{DOWN}");
}
}
At last subscribe the Leave event of the TextBox and do following in the event method:
private void OnTextBoxLeave(object sender, EventArgs e)
{
if (treeView1.SelectedNode != null)
{
treeView1.SelectedNode.Text = textBox1.Text;
}
}
And, voilá it should work like you expected it...

If you want to focus on it , you can use usercontrol. you can put your textbox on usercontrol and set focus of this textbox on usercontrol using set properties on treeview select.

No you may not, only one control may be in focus at any given time.
See Moonlight's comment for one way to achieve the behavior that you seek.

How to validate array of text boxes

I am using c# winform.
I have 2dimensional array of text boxes I want them to accept only Letters from A-I I've created the method but that works for only one text box.
Here is my code:
textbox[i,j].Validated+=new EventHandler(TextBox_KeyPress);
private void TextBox_KeyPress(object sender, EventArgs e)
{
bool bTest = txtRegExStringIsValid(textbox[1,1].Text.ToString());
ToolTip tip = new ToolTip();
if (bTest == false)
{
tip.Show("Only A-I", textbox[1,1], 2000);
textbox[1,1].Text = " ";
}
}
private bool txtRegExStringIsValid(string textToValidate)
{
Regex TheRegExpression;
string TheTextToValidate;
string TheRegExTest = #"^[A-I ]+$";
TheTextToValidate = textToValidate;
TheRegExpression = new Regex(TheRegExTest);
if (TheRegExpression.IsMatch(TheTextToValidate))
{
return true;
}
else
{
return false;
}
}
Can anyone please guide what should I do make this code work for all text boxes?

if this works for textbox[1,1] you could register your private void TextBox_KeyPress(object sender, EventArgs e) as eventhandler for all your textboxes and instead of textbox[1,1] you could use ((TextBox)sender)

i want text boxes to accept only letters from a-i actually i am trying to make sudoku
There's a much simpler solution than regular expressions, and you don't even need to handle the Validated event to implement it.
In a situation like this, where there are only certain characters that you want to prevent the user from entering, handling the KeyDown event is a much better solution. The user gets immediate feedback that the letter they tried to enter was not accepted. The alternative (the Validating and Validated events) actually wait until the user tries to leave the textbox to rudely alert them that their input was invalid. Especially for a game, this tends to break concentration and isn't particularly user-friendly.
Doing it this way also makes it irrelevant which individual textbox raised the event. Instead, you will handle it the same way for all of the textboxes—by completely ignoring all invalid input.
Here's what I'd do:
First, attach a handler method to your textbox's KeyDown event. You can do this from the Properties window in the designer, or you can do it through code, as you have in the question:
textbox[i,j].KeyDown += TextBox_KeyDown;
Then, you need to put the logic into your event handler method that determines if the key that the user just pressed is in the allowed range (A through I), or outside of it:
private void TextBox_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
// Determine if the keystroke was a letter between A and I
if (e.KeyCode < Keys.A || e.KeyCode > Keys.I)
{
// But allow through the backspace key,
// so they can correct their mistakes!
if (e.KeyCode != Keys.Back)
{
// Now we've caught them! An invalid key was pressed.
// Handle it by beeping at the user, and ignoring the key event.
System.Media.SystemSounds.Beep.Play();
e.SuppressKeyPress = true;
}
}
}
If you want to restrict the user to typing in only one letter, you can add code to handle that in the above method, or you can take an even simpler route and let the textbox control handle it for you automatically. To do that, set the MaxLength property of the textbox to true, either in the designer or through code:
textbox[i,j].MaxLength = true;

Check the text of the sender instead of whatever textbox[1,1] is.

Use the sender parameter of the event handler to identify the textbox responsible for the event.

The first thing that will help you is casting the sender of your event to a TextBox like this:
(Also, as Cody Gray said, this is a TextBox_Validated event, not a KeyPress event so I've renamed it appropriately)
private void TextBox_Validated(object sender, EventArgs e)
{
TextBox tb = sender as TextBox()
if (sender == null)
return;
bool bTest = txtRegExStringIsValid(tb.Text.ToString());
ToolTip tip = new ToolTip();
if (bTest == false) {
tip.Show("Only A-I", tb, 2000);
tb .ext = " ";
}
Next you need to actually get into that code for every textbox. There are two obvious approaches to that, you can either assign the eventhandler to each textbox in the array or you can use a custom textbox which always does this validation and then add that to your array.
Assign eventhandler to textboxes
foreach(var tb in textbox)
{
tb.Validated += new EventHandler(TextBox_KeyPress);
}
Create custom textbox control
Create the custom text box control (Add a user control to the project) and then just use it exactly as you would a normal textbox.
public partial class ValidatingTextBox: TextBox
{
public ValidatingTextBox()
{
InitializeComponent();
}
protected override void OnValidating(CancelEventArgs e)
{
bool bTest = txtRegExStringIsValid(this.Text.ToString());
ToolTip tip = new ToolTip();
if (bTest == false)
{
tip.Show("Only A-I", this, 2000);
this.Text = " ";
}
}
private bool txtRegExStringIsValid(string textToValidate)
{
// Exactly the same validation logic as in the same method on the form
}
}