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C# Number Only Field with Backspace and Paste function

Posted on 2008-10-28
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Last Modified: 2012-05-05
Hello all,

I am working in C# 2008 Express and want to have my text field only accept numbers however still allow backspace and paste insertion.  I have pasted in what i have thus far which allows the just numbers and the backspace but I am failing to conquer the paste function.  Any help would be great thanks.

        private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            //if (!Char.IsDigit(e.KeyChar)||!Char.IsControl(e.KeyChar))
            if ((!Char.IsDigit(e.KeyChar)) && (e.KeyChar != Convert.ToChar(Keys.Back)))
                e.Handled = true;
        }
0
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Question by:Andrew Bass
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  • 2
6 Comments
 
LVL 1

Expert Comment

by:Nullable
ID: 22827748
Use this Code in the KeyDown Event



private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
    // For Past Action
    if (e.Modifiers == Keys.Control && e.KeyCode == Keys.V)
        return;
    e.SuppressKeyPress = true;
}

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LVL 26

Expert Comment

by:Anurag Thakur
ID: 22828366
void textBox1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.V && (e.Modifiers & Keys.Control) != Keys.None)
    {
        TextBox tb = sender as TextBox;
        string textToPaste =  Clipboard.GetText();
        tb.Paste();
        e.Handled = true;
        e.SuppressKeyPress = true;
        Console.WriteLine("Pasted: {0}", textToPaste);
    }
}

But that won't intercept the user clicking on Edit->Paste...

You can do that by inherting new control from the text box control and overriding WndProc in order to detect WM_PASTE message. Here is an example for an overriden WndProc

private const int WM_PASTE = 0x0302;
  protected override void WndProc(ref Message m)
  {
   if (m.Msg == WM_PASTE)
   {
    MessageBox.Show("Paste");
   }
   base.WndProc(ref m);
  }
0
 
LVL 1

Expert Comment

by:Nullable
ID: 22828389
in this code  :
void textBox1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.V && (e.Modifiers & Keys.Control) != Keys.None)
    {
        TextBox tb = sender as TextBox;
        string textToPaste =  Clipboard.GetText();
        tb.Paste();
        e.Handled = true;
        e.SuppressKeyPress = true;
        Console.WriteLine("Pasted: {0}", textToPaste);
    }
}

Shift + V is not work
0
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If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.

 
LVL 1

Author Comment

by:Andrew Bass
ID: 22832003
When I use your code i continue to get expected errors.
To clarify I DO WANT end users to be able to paste numbers into the text box field.  I have attached the coding in a txt doc if there are any ideas how to fix this up it would be appreciated.  Thanks
        private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            //if (!Char.IsDigit(e.KeyChar)||!Char.IsControl(e.KeyChar))
            if ((!Char.IsDigit(e.KeyChar)) && (e.KeyChar != Convert.ToChar(Keys.Back)))
                e.Handled = true;
        }
 
        private void textBox1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.V && (e.Modifiers & Keys.Control) != Keys.None)
                {
                TextBox tb = sender as TextBox;
                string textToPaste = Clipboard.GetText();
                tb.Paste();
                e.Handled = true;
                e.SuppressKeyPress = true;
                Console.WriteLine("Pasted: {0}", textToPaste);
                }
        }

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Accepted Solution

by:
Nullable earned 500 total points
ID: 22870274
i have writen a Control
it is a FilteredTextbox
i Place my code for u with a sample

it have this featurse :
numeric filterDecimal filter ( numeric + float point (.))Email filter Custom Filter ( set a char set for desire)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Text.RegularExpressions;
 
namespace BM
{
    /// <summary>
    /// writed by Behrooz Mohammadi ( Nullabel )
    /// behrooz_pro@yahoo.com
    /// </summary>
    [DefaultBindingProperty("IntValue")]
    public partial class FilteredTextBox : TextBox
    {
        public FilteredTextBox()
        {
            InitializeComponent();
        }
 
        protected override void OnKeyPress(KeyPressEventArgs e)
        {
            base.OnKeyPress(e);
                                                                       
            if (!Active || e.KeyChar == '\b')
                return;
 
            if (Email)
            {
                return;
            }
            else
            {
                if (CustomFilter != "")
                {
                    if (CustomFilter.Contains(e.KeyChar))
                        return;
                }
 
                if (Numeric)
                {
                    if (char.IsNumber(e.KeyChar))
                        return;
                }
 
                if (AllowDecimals && !Text.Contains("."))
                    if (e.KeyChar == '.')
                        return;
            }
 
            e.Handled = true;
        }
 
        [Category("Setting")]
        public bool Active { get; set; }
 
        [Category("Setting")]
        public bool Numeric { get; set; }
 
        [Category("Setting")]
        public bool Email { get; set; }
 
        string _CustomFilter = "";
        private bool _allowDecimals = false;
        private string LastStr = "";
 
        [Category("Setting")]
        public string CustomFilter
        {
            get { return _CustomFilter; }
            set
            {
                _CustomFilter = value;
            }
        }
 
        [Category("Setting")]
        public bool AllowDecimals
        {
            get { return _allowDecimals; }
            set { _allowDecimals = value; }
        }
 
        [Bindable(true)]
        [Category("Setting")]
        public int? IntValue
        {
            get
            {
                if (string.IsNullOrEmpty(Text))
                    return null;
 
                int A;
                if (int.TryParse(Text, out A))
                    return A;
                else
                    return null;
            }
            set
            {
                if (value.HasValue)
                    this.Text = value.Value.ToString();
                else
                    Text = "";
            }
        }
 
        [Bindable(true)]
        [Category("Setting")]
        public decimal? DecimalValue
        {
            get
            {
                if (string.IsNullOrEmpty(Text))
                    return null;
 
                decimal A;
                if (decimal.TryParse(Text, out A))
                    return A;
                else
                    return null;
            }
            set
            {
                if (value.HasValue)
                    this.Text = value.Value.ToString();
                else
                    Text = "";
            }
        }
 
        protected override void OnTextChanged(EventArgs e)
        {
            if (!Active || string.IsNullOrEmpty(Text))
                return;
 
            if (Numeric)
                if (_allowDecimals)
                {
                    decimal k;
                    if (!decimal.TryParse(Text, out k))
                    {
                        int x = SelectionStart, l = SelectionLength;
                        this.Text = LastStr;
                        SelectionStart = x;
                        SelectionLength = l;
                        return;
                    }
                }
                else
                {
                    int k;
                    if (!int.TryParse(Text, out k))
                    {
                        int x = SelectionStart, l = SelectionLength;
                        this.Text = LastStr;
                        SelectionStart = x;
                        SelectionLength = l;
                        return;
                    }
                }
            LastStr = Text;
            base.OnTextChanged(e);
        }
 
        private void FilteredTextBox_Validating(object sender, CancelEventArgs e)
        {
            if (Email)
            {
                if (string.IsNullOrEmpty(Text))
                    return;
 
                string strRegex = @"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" +
                          @"\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" +
                          @".)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$";
                Regex re = new Regex(strRegex);
                if (re.IsMatch(Text))
                    return;
                else
                {
                    e.Cancel = true;
                    MessageBox.Show("Enter Valid Email.");
                }
            }
        }
    }
}
 
// Designer.cs file :
 
namespace BM
{
    partial class FilteredTextBox
    {
        /// <summary> 
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;
 
        /// <summary> 
        /// Clean up any resources being used.
        /// </summary>        
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }
 
        #region Component Designer generated code
 
        /// <summary> 
        /// Required method for Designer support - do not modify 
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.SuspendLayout();
            // 
            // FilteredTextBox
            // 
            this.Validating += new System.ComponentModel.CancelEventHandler(this.FilteredTextBox_Validating);
            this.ResumeLayout(false);
 
        }
 
        #endregion
    }
}

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FilterTextbox.zip
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Author Closing Comment

by:Andrew Bass
ID: 31511010
Thanks for your help Nullable and the thoroughness!
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