CODEWITHSUNDEEP
c#winformstextbox
Lijina
Lijina

Reputation: 297

How to make a TextBox accept only alphabetic characters?

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

Upvotes: 20

Views: 179555

Answers (18)

Hamas
Hamas

Reputation: 7

textbox1.Text = string.Concat(textbox1.Text.Where(char.IsLetter));

This line of code is working with me perfectly with filter input and allow just letters, either with TextChanged handle or KeyPress handle.

Upvotes: 0

armin567ip
armin567ip

Reputation: 1

Try this one. Spaces and shortcut keys work

 if (!char.IsControl(e.KeyChar) && !char.IsLetter(e.KeyChar) && !char.IsSeparator(e.KeyChar))
        {
            e.Handled = true;
        }

Upvotes: 0

sfaj
sfaj

Reputation: 1

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

Upvotes: 0

Dong Y
Dong Y

Reputation: 39

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 = "";
            }
        }

Upvotes: 0

StuKay
StuKay

Reputation: 317

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.

Upvotes: 3

favoretti
favoretti

Reputation: 30207

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);
    }
}

Upvotes: 19

anagha
anagha

Reputation: 63

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

Upvotes: 0

Josipzuzic
Josipzuzic

Reputation: 11

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;
}

Upvotes: 1

Niteen4u
Niteen4u

Reputation: 31

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");
        }

Upvotes: 1

Abu Bakar
Abu Bakar

Reputation: 37

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

Upvotes: 1

Sanket7496
Sanket7496

Reputation: 1

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");
        }
    }

Upvotes: 0

Sohail Malik
Sohail Malik

Reputation: 335

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;
    }

Upvotes: 3

farhad
farhad

Reputation: 11

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

Upvotes: 1

user1737728
user1737728

Reputation: 51

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

Upvotes: 5

Akshita
Akshita

Reputation: 867

Write Code in Text_KeyPress Event as

 private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {

        if (!char.IsLetter(e.KeyChar))
        {
            e.Handled = true;
        }
    }

Upvotes: 4

Thomas Siranjeevi
Thomas Siranjeevi

Reputation: 124

        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

Upvotes: 2

V4Vendetta
V4Vendetta

Reputation: 38230

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.

Upvotes: 19

Pavel Donchev
Pavel Donchev

Reputation: 1899

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.

Upvotes: 4

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