Question

In my window application I need masked textbox which accept real decmal numbers.

eg.
1) 1.56
2) 22.34
3) 123.34
4) 12312.34
This all value should be valid.

Can anyone tell me how can I do this?
And ya if anyone have better solution for real decimal numbers, instead of this masked TextBox
than I love to see it.
Thanks…

Answer 1

Use a custom control like this one (modify it to fulfill your needs):

using System; 
using System.ComponentModel; 
using System.Text; 
using System.Windows.Forms; 
using System.Drawing; 

namespace CustomControls 
{ 
    public enum PasteRejectReasons 
    { 
        Unknown = 0, 
        NoData, 
        InvalidCharacter, 
        Accepted 
    } 

    public class DecimalTextBox : TextBox 
    { 
        public const int WM_PASTE = 0x0302; 
        public event EventHandler<KeyRejectedEventArgs> KeyRejected; 
        public event EventHandler<PasteEventArgs> PasteRejected; 

        private bool _DecimalSeparator = false; 
        private int _Precision; 

        public new HorizontalAlignment TextAlign 
        { 
            get { return base.TextAlign; } 
            set { base.TextAlign = value; } 
        } 

        public int Precision 
        { 
            get { return _Precision; } 
            set { _Precision = value; } 
        } 

        public DecimalTextBox() 
        { 
            TextAlign = HorizontalAlignment.Right; 
            Precision = 3; 
        } 

        protected override void OnGotFocus(EventArgs e) 
        { 
            SelectAll(); 
            base.OnGotFocus(e); 
        } 

        protected override void OnKeyDown(KeyEventArgs e) 
        { 
            bool validate = true; 

            if (Text.Contains(".") || Text.Contains(",")) 
            { 
                int indexSep; 
                string[] split; 
                string partiDecimal = ""; 

                if (Text.Contains(".")) 
                    indexSep = Text.IndexOf('.'); 
                else 
                    indexSep = Text.IndexOf(','); 

                split = Text.Split(new char[] { ',', '.' }); 
                partiDecimal += split[1]; 

                if (partiDecimal.Length >= Precision) 
                    if (SelectionStart > Text.Length - (partiDecimal.Length + 1)) 
                        validate = false; 
            } 

            bool result = true; 

            bool validateKeys = (e.KeyCode == Keys.Enter); 

            bool numericKeys = ( 
                ((e.KeyCode >= Keys.D0 && e.KeyCode <= Keys.D9) || 
                (e.KeyCode >= Keys.NumPad0 && e.KeyCode <= Keys.NumPad9)) 
                && e.Modifiers != Keys.Shift 
                && validate); 

            bool ctrlA = e.KeyCode == Keys.A && e.Modifiers == Keys.Control; 

            bool editKeys = ( 
                (e.KeyCode == Keys.Z && e.Modifiers == Keys.Control) || 
                (e.KeyCode == Keys.X && e.Modifiers == Keys.Control) || 
                (e.KeyCode == Keys.C && e.Modifiers == Keys.Control) || 
                (e.KeyCode == Keys.V && e.Modifiers == Keys.Control) || 
                e.KeyCode == Keys.Delete || 
                e.KeyCode == Keys.Back); 

            bool navigationKeys = ( 
                e.KeyCode == Keys.Up || 
                e.KeyCode == Keys.Right || 
                e.KeyCode == Keys.Down || 
                e.KeyCode == Keys.Left || 
                e.KeyCode == Keys.Home || 
                e.KeyCode == Keys.End); 

            bool decimalSeparator = (( 
                e.KeyCode == Keys.Decimal || 
                e.KeyValue == 190 || 
                e.KeyValue == 188)&& 
                TextLength != 0 && 
                SelectionLength == 0); 

            if (decimalSeparator)  
            { 
                if (!_DecimalSeparator) 
                    _DecimalSeparator = true; 
                else 
                    decimalSeparator = false; 
            } 

            if (!(numericKeys || editKeys || navigationKeys || decimalSeparator || validateKeys)) 
            { 
                if (ctrlA)
                    SelectAll();

                result = false; 
            } 

            if (!result)
            { 
                e.SuppressKeyPress = true; 
                e.Handled = true; 

                if (!ctrlA)
                    OnKeyRejected(new KeyRejectedEventArgs(e.KeyCode)); 
            } 
            else 
                base.OnKeyDown(e); 
        } 

        protected override void OnKeyPress(KeyPressEventArgs e) 
        { 
            if (e.KeyChar == ';' || e.KeyChar == '?') 
            { 
                if (!(Text.Contains(",") || Text.Contains("."))) 
                    _DecimalSeparator = false; 
                e.Handled = true; 
            } 
        } 

        protected override void OnTextChanged(EventArgs e) 
        { 
            bool invalid = false; 
            int i = 0; 
            foreach (char c in Text) // Check for any non digit characters. 
            { 
                if (!(char.IsDigit(c) || c == ',' || c == '.')) 
                { 
                    invalid = true; 
                    break; 
                } 

                if (c == ',' || c == '.') 
                    i++; 
            } 

            if (i == 0) 
                _DecimalSeparator = false; 
            else if (i > 1) 
                invalid = true; 

            if (invalid) 
            { 
                Text = ""; 
                return; 
            } 

            if (Text.Contains(".") || Text.Contains(",")) 
            { 
                string charSep = ""; 
                string[] split; 
                string partiEntier = ""; 

                if (Text.Contains(".")) 
                    charSep = "."; 
                else 
                    charSep = ","; 

                split = Text.Split(new char[] { ',', '.' }); 
                partiEntier += split[0]; 
                if (partiEntier == "") 
                    Text = "0" + charSep + split[1]; 
            } 
            base.OnTextChanged(e); 
        } 

        protected override void WndProc(ref Message m) 
        { 
            if (m.Msg == WM_PASTE) 
            { 
                PasteEventArgs e = CheckPasteValid(); 
                if (e.RejectReason != PasteRejectReasons.Accepted) 
                { 
                    m.Result = IntPtr.Zero; 
                    OnPasteRejected(e); 
                    return; 
                } 
            } 
            base.WndProc(ref m); 
        } 

        private PasteEventArgs CheckPasteValid() 
        { 
            PasteRejectReasons rejectReason = PasteRejectReasons.Accepted; 
            string originalText = Text; 
            string clipboardText = string.Empty; 
            string textResult = string.Empty; 

            try 
            { 
                clipboardText = Clipboard.GetText(TextDataFormat.Text); 
                if (clipboardText.Length > 0)
                { 

                    textResult = ( 
                        Text.Remove(SelectionStart, SelectionLength).Insert(SelectionStart, clipboardText)); 
                    foreach (char c in clipboardText)
                    { 
                        if (!char.IsDigit(c)) 
                        { 
                            rejectReason = PasteRejectReasons.InvalidCharacter; 
                            break; 
                        } 
                    } 
                } 
                else 
                    rejectReason = PasteRejectReasons.NoData; 
            } 
            catch 
            { 
                rejectReason = PasteRejectReasons.Unknown; 
            } 
            return new PasteEventArgs(originalText, clipboardText, textResult, rejectReason); 
        } 

        protected virtual void OnKeyRejected(KeyRejectedEventArgs e) 
        { 
            EventHandler<KeyRejectedEventArgs> handler = KeyRejected; 
            if (handler != null) 
                handler(this, e); 
        } 

        protected virtual void OnPasteRejected(PasteEventArgs e) 
        { 
            EventHandler<PasteEventArgs> handler = PasteRejected; 
            if (handler != null) 
                handler(this, e); 
        } 
    } 
}