can't determine '.' keychar for a textbox KeyPress event - c#

I use below code to not allowing any character except numbers in a textbox ... but it allows '.' character! I don't want it to allow dot.
private void txtJustNumber_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsDigit((char)(e.KeyChar)) &&
e.KeyChar != ((char)(Keys.Enter)) &&
e.KeyChar != (char)(Keys.Delete) &&
e.KeyChar != (char)(Keys.Back)&&
e.KeyChar !=(char)(Keys.OemPeriod))
{
e.Handled = true;
}
}


use this:
if (!char.IsDigit((char)(e.KeyChar)) &&
e.KeyChar != ((char)(Keys.Enter)) &&
(e.KeyChar != (char)(Keys.Delete) || e.KeyChar == Char.Parse(".")) &&
e.KeyChar != (char)(Keys.Back)
)
it is because Keys.Delete's char value is 46 which is the same as '.'. I do not know why it likes this.


You could try this instead (where textBox1 would be your textbox):
// Hook up the text changed event.
textBox1.TextChanged += textBox1_TextChanged;
...
private void textBox1_TextChanged(object sender, EventArgs e)
{
// Replace all non-digit char's with empty string.
textBox1.Text = Regex.Replace(textBox1.Text, #"[^\d]", "");
}
Or
// Save the regular expression object globally (so it won't be created every time the text is changed).
Regex reg = new Regex(#"[^\d]");
private void textBox1_TextChanged(object sender, EventArgs e)
{
if (reg.IsMatch(textBox1.Text))
textBox1.Text = reg.Replace(textBox1.Text, ""); // Replace only if it matches.
}


//This is the shortest way
private void txtJustNumber_KeyPress(object sender, KeyPressEventArgs e)
{
if(!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar))
{
e.Handled = true;
}
}


try this code for your problem in keypress event :
private void txtMazaneh_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsDigit(e.KeyChar) && (int)e.KeyChar != 8 ||(e.KeyChar= .))
e.Handled = true;
}

Related

How to Constraint on TextBox in C#?

I try constraint for TextBox in C#. I succesfull this for users can put only numbers:
private void TxtID_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = !char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar);
}
Now, I wonder how can users just write 11 char in TextBox? I try char.Max or Min but i can't in the KeyPress event.

Something like this:
public MyForm()
{
InitializeComponent();
// At most 11 characters
TxtID.MaxLength = 11;
}
private void TxtID_KeyPress(object sender, KeyPressEventArgs e)
{
// char.IsDigit is too wide: it returns true on any unicode digit (e.g. Persian ones)
e.Handled = (e.KeyChar < '0' || e.KeyChar > '9') && !char.IsControl(e.KeyChar);
}
// On Paste we should validate the input:
// what if user copy "bla-bla-bla 1234" and paste it to TxtID?
private void TxtID_TextChanged(object sender, EventArgs e)
{
Control ctrl = (sender as Control);
string value = string.Concat(ctrl
.Text
.Where(c => c >= '0' && c <= '9'));
if (value != ctrl.Text)
ctrl.Text = value;
}

Prevent continue Typing in TextBox When a Char is Entered

I have a textbox which user should type a price in it.
I need to prevent continue typing if price starts with 0.
For example user can not type "000" or "00009".
I tried this on KeyPress, but nothing!
if (txt.Text.StartsWith("0"))
return; Or e.Handeled = true;

try this:
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
//only allow digit and (.) and backspace
if ((e.KeyChar < '0' || e.KeyChar > '9') && e.KeyChar != '\b' && e.KeyChar != '.')
{
e.Handled = true;
}
var txt = sender as TextBox;
//only allow one dot
if (txt.Text.Contains('.') && e.KeyChar == (int)'.')
{
e.Handled = true;
}
//if 0, only allow 0.xxxx
if (txt.Text.StartsWith("0")
&& !txt.Text.StartsWith("0.")
&& e.KeyChar != '\b'
&& e.KeyChar != (int)'.')
{
e.Handled = true;
}
}

You could use the TextChanged-event for this.
private void textBox1_TextChanged(object sender, EventArgs e)
{
if (this.textBox1.Text == "0") this.textBox1.Text = "";
}
This will only work, if the TextBox is empty on startup.

I solved it Myself:
private void txtPrice_KeyPress(object sender, KeyPressEventArgs e)
{
if (txtPrice.Text.StartsWith("0") && !char.IsControl(e.KeyChar))
{
e.Handled = true;
return;
}
}

keypress event for number in WinForm TextBox in C#

I want to limit user to type just numbers in TextBox.
I add this code In keypress Event:
private void txtPartID_KeyPress(object sender, KeyPressEventArgs e)
{
if (((e.KeyChar >= '0') && (e.KeyChar <= '9')) == false)
{
e.Handled = true;
}
}
but after that BackSpace key don't work for this TextBox. How can I change this?

You can check for backspace using this,
if(e.KeyChar == '\b')
And better way to check only for numbers is
private void txtPartID_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = !(Char.IsNumber(e.KeyChar) || e.KeyChar == 8);
}

private void TxtBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (!(Char.IsDigit(e.KeyChar) && (e.KeyChar == (char)Keys.Back)))
e.Handled = true;
}

I think you should handle both back key and delete key.
if (!(Char.IsDigit(e.KeyChar) && (e.KeyChar == (char)Keys.Back)&& (e.KeyChar == (char)Keys.Delete)))
e.Handled = true;

You can use it
private void txtColumn_KeyPress(object sender, KeyPressEventArgs e)
{
if (((e.KeyChar >= '0') && (e.KeyChar <= '9') || (e.KeyChar == (char)Keys.Back)) == false)
{
e.Handled = true;
}
}

allow just number in a gridviewcell on editing

I have a gridview in my C# windows application ... It allowed to be edited and I want a special cell (named "Price") to just allow number on keypress ... I use the code below for texboxes to just allow numbers ... in which event of grid view should I write this code?
private void txtJustNumber_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsDigit((char)(e.KeyChar)) &&
e.KeyChar != ((char)(Keys.Enter)) &&
(e.KeyChar != (char)(Keys.Delete) || e.KeyChar == Char.Parse(".")) &&
e.KeyChar != (char)(Keys.Back))
{
e.Handled = true;
}
}

You can use CellValidating event of DataGridView.
private void dataGridView1_CellValidating(object sender,
DataGridViewCellValidatingEventArgs e)
{
// Validate the Price entry.
if (dataGridView1.Columns[e.ColumnIndex].Name == "Price")
{
}
}

thx guys ... I used below code and my problem resolved ...
public Form1()
{
InitializeComponent();
MyDataGridViewInitializationMethod();
}
private void MyDataGridViewInitializationMethod()
{
gvFactorItems.EditingControlShowing +=
new DataGridViewEditingControlShowingEventHandler(gvFactorItems_EditingControlShowing);
}
private void gvFactorItems_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
e.Control.KeyPress += new KeyPressEventHandler(Control_KeyPress); ;
}
private void Control_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsDigit((char)(e.KeyChar)) &&
e.KeyChar != ((char)(Keys.Enter)) &&
(e.KeyChar != (char)(Keys.Delete) || e.KeyChar == Char.Parse(".")) &&
e.KeyChar != (char)(Keys.Back))
{
e.Handled = true;
}
}

I think you should take a look at this, it will help :-
DataGridView keydown event not working in C#

How to make a TextBox accept only alphabetic characters?

How can I make a TextBox only accept alphabetic characters with spaces?

You could use the following snippet:
private void textBox1_TextChanged(object sender, EventArgs e)
{
if (!System.Text.RegularExpressions.Regex.IsMatch(textBox1.Text, "^[a-zA-Z ]"))
{
MessageBox.Show("This textbox accepts only alphabetical characters");
textBox1.Text.Remove(textBox1.Text.Length - 1);
}
}

You can try by handling the KeyPress event for the textbox
void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = !(char.IsLetter(e.KeyChar) || e.KeyChar == (char)Keys.Back);
}
Additionally say allow backspace in case you want to remove some text, this should work perfectly fine for you
EDIT
The above code won't work for paste in the field for which i believe you will have to use TextChanged event but then it would be a bit more complicated with you having to remove the incorrect char or highlight it and place the cursor for the user to make the correction Or maybe you could validate once the user has entered the complete text and tabs off the control.

private void textbox1_KeyDown_1(object sender, KeyEventArgs e)
{
if (e.Key >= Key.A && e.Key <= Key.Z)
{
}
else
{
e.Handled = true;
}
}

The simplest way is to handle the TextChangedEvent and check what's been typed:
string oldText = string.Empty;
private void textBox2_TextChanged(object sender, EventArgs e)
{
if (textBox2.Text.All(chr => char.IsLetter(chr)))
{
oldText = textBox2.Text;
textBox2.Text = oldText;
textBox2.BackColor = System.Drawing.Color.White;
textBox2.ForeColor = System.Drawing.Color.Black;
}
else
{
textBox2.Text = oldText;
textBox2.BackColor = System.Drawing.Color.Red;
textBox2.ForeColor = System.Drawing.Color.White;
}
textBox2.SelectionStart = textBox2.Text.Length;
}
This is a regex-free version if you prefer. It will make the text box blink on bad input.
Please note that it also seems to support paste operations as well.

Write Code in Text_KeyPress Event as
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsLetter(e.KeyChar))
{
e.Handled = true;
}
}

This one is working absolutely fine...
private void manufacturerOrSupplierTextBox_KeyPress(object sender, KeyPressEventArgs e)
{
if (char.IsControl(e.KeyChar) || char.IsLetter(e.KeyChar))
{
return;
}
e.Handled = true;
}

This solution uses regular expressions, does not allow invalid characters to be pasted into the text box and maintains the cursor position.
using System.Text.RegularExpressions;
int CursorWas;
string WhatItWas;
private void textBox1_Enter(object sender, EventArgs e)
{
WhatItWas = textBox1.Text;
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
if (Regex.IsMatch(textBox1.Text, "^[a-zA-Z ]*$"))
{
WhatItWas = textBox1.Text;
}
else
{
CursorWas = textBox1.SelectionStart == 0 ? 0 : textBox1.SelectionStart - 1;
textBox1.Text = WhatItWas;
textBox1.SelectionStart = CursorWas;
}
}
Note: textBox1_TextChanged recursive call.

if (System.Text.RegularExpressions.Regex.IsMatch(textBox1.Text, "^[a-zA-Z]+$"))
{
}
else
{
textBox1.Text = textBox1.Text.Remove(textBox1.Text.Length - 1);
MessageBox.Show("Enter only Alphabets");
}
Please Try this

private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar >= '0' && e.KeyChar <= '9')
e.Handled = true;
else
e.Handled = false;
}

Try This
private void tbCustomerName_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = !(char.IsLetter(e.KeyChar) || e.KeyChar == (char)Keys.Back||e.KeyChar==(char)Keys.Space);
}
It Allows White Spaces Too

you can try following code that alert at the time of key press event
private void tbOwnerName_KeyPress(object sender, KeyPressEventArgs e)
{
//===================to accept only charactrs & space/backspace=============================================
if (e.Handled = !(char.IsLetter(e.KeyChar) || e.KeyChar == (char)Keys.Back || e.KeyChar == (char)Keys.Space))
{
e.Handled = true;
base.OnKeyPress(e);
MessageBox.Show("enter characters only");
}

Here is my solution and it works as planned:
string errmsg = "ERROR : Wrong input";
ErrorLbl.Text = errmsg;
if (e.Handled = !(char.IsLetter(e.KeyChar) || e.KeyChar == (char)Keys.Back || e.KeyChar == (char)Keys.Space))
{
ErrorLbl.Text = "ERROR : Wrong input";
}
else ErrorLbl.Text = string.Empty;
if (ErrorLbl.Text == errmsg)
{
Nametxt.Text = string.Empty;
}

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsControl(e.KeyChar) && !char.IsLetter(e.KeyChar) &&
(e.KeyChar !='.'))
{
e.Handled = true;
MessageBox.Show("Only Alphabets");
}
}

Try following code in KeyPress event of textbox
if (char.IsLetter(e.KeyChar) == false &
Convert.ToString(e.KeyChar) != Microsoft.VisualBasic.Constants.vbBack)
e.Handled = true

works for me, even though not the simplest one.
private void Alpha_Click(object sender, EventArgs e)
{
int count = 0;
foreach (char letter in inputTXT.Text)
{
if (Char.IsLetter(letter))
{
count++;
}
else
{
count = 0;
}
}
if (count != inputTXT.Text.Length)
{
errorBox.Text = "The input text must contain only alphabetic characters";
}
else
{
errorBox.Text = "";
}
}

This works fine as far as characters restriction, Any suggestions on error msg prompt with my code if it's not C OR L
Private Sub TXTBOX_TextChanged(sender As System.Object, e As System.EventArgs) Handles TXTBOX.TextChanged
Dim allowed As String = "C,L"
For Each C As Char In TXTBOX.Text
If allowed.Contains(C) = False Then
TXTBOX.Text = TXTBOX.Text.Remove(TXTBOX.SelectionStart - 1, 1)
TXTBOX.Select(TXTBOX.Text.Count, 0)
End If
Next
End Sub

Try this one. Spaces and shortcut keys work
if (!char.IsControl(e.KeyChar) && !char.IsLetter(e.KeyChar) && !char.IsSeparator(e.KeyChar))
{
e.Handled = true;
}

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