C#winform中Textbox.text中让输入的信息只能是数字不能是符号或字母

Question

 如何在C#winform中 Textbox.text中让输入的信息只能是数字，不能是符号或字母，这个if不知该怎么写尤其是（不能是符号或字母）！，谢谢各位大侠！不胜感激！，联系人：小史，QQ723201219

Answer 1

使用异常处理啊！看输入的文本能不能转换为INT型的
不能就把文本清空`

Answer 2

在对文本框内容验证的函数中进行如下工作:
先获取文本内容,用INT32的PARASE函数进行串格式化,但将它放在TRY块内,如果是合法的数字串返回1,否则在CATCH子句中捕获异常,并返回-1

Answer 3

用Text控件的KeyPress事件，并且输入以下代码
private void txtPrice_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!(e.KeyChar>='0'&& e.KeyChar<='9'|| e.KeyChar==8))
            {
                e.Handled = true;
            }
        }

Answer 4

自己扩展一下TextBox.以下是我用的一个NumberBox控件源码，可以参考一下。功能是：只能输入数字（含+、-号）；TextBox为disable时还可以设定字体颜色及textbox边框颜色（这可是当初客户比较苛刻的要求，说disable后字体颜色太淡了，看不清）using System;
using System.ComponentModel;
using System.Collections;
using System.Diagnostics;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Drawing2D;namespace USWinControls
{
    ///<summary>
    ///NumberBox 的摘要说明。
    ///</summary>
    [ToolboxItem(true)]
    [ToolboxBitmap(typeof(TextBox)), Description("UBIQ NumberBox")]
    public class NumberBox : System.Windows.Forms.TextBox
    {
        /// <summary> 
        /// 获得当前进程，以便重绘控件 
         /// </summary> 
        /// <param name="hWnd"></param> 
        /// <returns></returns> 
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        static extern IntPtr GetWindowDC(IntPtr hWnd);
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);        #region  Constractor
        public NumberBox()
            : base()
        {
            PermitChars = new char[13];
            Init();
        }
        #endregion        #region Property
        private double _MaxValue;
        private double _MinValue;
        private char[] _PermitChars;
        private int _DecimalLength;
        private double _DefaultValue;        /// <summary> 
        /// 边框颜色 
        /// </summary> 
        private Color _BorderColor = Color.FromArgb(0xA7, 0xA6, 0xAA);        /// <summary> 
        /// 失效时的字符颜色 
        /// </summary> 
        private Color _DisableForeColor = Color.FromName("DimGray");        /// <summary> 
        /// 失效时的背景颜色 
        /// </summary> 
        private Color _DisableBackColor = Color.FromName("Control");        public double MaxValue
        {
            get { return _MaxValue; }            set { _MaxValue = value; }
        }        public double MinValue
        {
            get { return _MinValue; }
            set { _MinValue = value; }
        }        public double DefaultValue
        {
            get { return _DefaultValue; }
            set
            {
                _DefaultValue = value;
                base.Text = _DefaultValue.ToString();
            }
        }        public char[] PermitChars
        {
            get { return _PermitChars; }
            set { _PermitChars = value; }
        }
        public int DecimalLength
        {
            get { return _DecimalLength; }
            set { _DecimalLength = value; }
        }        /// <summary> 
        /// 边框颜色 
        /// </summary> 
        [Category("外观"),
       Description("获得或设置控件的边框颜色"),
       DefaultValue(typeof(Color), "#A7A6AA")]
        public Color BorderColor
        {
            get { return this._BorderColor; }
            set
            {
                this._BorderColor = value;
                this.Invalidate();
            }
        }        /// <summary>
        /// 失效时的字符颜色
        /// </summary>
        [DefaultValue(typeof(Color), "#A7A6AA")]
        [Description("失效时的字符颜色")]
        public Color DisableForeColor
        {
            get { return this._DisableForeColor; }
            set
            {
                this._DisableForeColor = value;
                this.Invalidate();
            }
        }        /// <summary>
        /// 失效时的背景色
        /// </summary>
        [DefaultValue(typeof(Color), "#A7A6AA")]
        [Description("失效时的背景色")]
        public Color DisableBackColor
        {
            get { return this._DisableBackColor; }
            set
            {
                this._DisableBackColor = value;
                this.Invalidate();
            }
        }        #endregion        #region  Initialize
        public void Init()
        {
            PermitChars = new char[] { (char)43, (char)45, (char)46, (char)48, (char)49, (char)50, (char)51, (char)52, (char)53, (char)54, (char)55, (char)56, (char)57 };
            DecimalLength = 0;
            MaxValue = 0;
            MinValue = 0;
            DefaultValue = 0;
        }        #endregion        #region  WndProc Method (Overrides)
        protected override void WndProc(ref System.Windows.Forms.Message m)
        {            const int WM_CHAR = 0x102;
            const int WM_PASTE = 0x302;
            const int WM_PAINT = 0x000f;            //
            switch (m.Msg)
            {
                case WM_CHAR:
                    KeyPressEventArgs eKeyPress = new KeyPressEventArgs((char)m.WParam.ToInt32());
                    OnChar(eKeyPress);                    if (eKeyPress.Handled)
                    {
                        return;
                    }                    break;                case WM_PASTE:
                    if (((PermitChars != null)) && (PermitChars.Length > 0))
                    {
                        OnPaste(new System.EventArgs());
                        return;
                    }                    break;            }            base.WndProc(ref m);            //
            if (WM_PAINT == m.Msg && !this.Enabled && m.HWnd == this.Handle)    //textbox disable
            {
                Graphics g = this.CreateGraphics();
                Rectangle rect;                //失效时的背景颜色
                rect = new Rectangle(0, 0, base.Size.Width - 1, base.Size.Height - 1);
                g.FillRectangle(new SolidBrush(DisableBackColor), rect);                //失效时的字符颜色
                //文字描画   
                int x = 0, y = 0;
                Size s = g.MeasureString(Text, Font).ToSize();                if (this.BorderStyle == BorderStyle.Fixed3D)
                    y = (Height - s.Height) / 2 - 1;
                else
                    y = (Height - s.Height) / 2;                switch (TextAlign)
                {
                    case HorizontalAlignment.Left:
                        x = 2;
                        break;
                    case HorizontalAlignment.Center:
                        if (s.Width > Width)
                            x = 2;
                        else
                            x = (Width - s.Width) / 2 + 2;
                        break;
                    case HorizontalAlignment.Right:
                        if (s.Width > Width)
                            x = 2;
                        else
                            x = Width - s.Width - 2;
                        break;
                }
                rect = new Rectangle(x, y, base.Size.Width, base.Size.Height);
                g.DrawString(base.Text, base.Font, new SolidBrush(DisableForeColor), rect);
                g.Dispose();
            }
            //
            if (m.Msg == 0xf || m.Msg == 0x133)
            {
                IntPtr hDC = GetWindowDC(m.HWnd);
                if (hDC.ToInt32() == 0)
                {
                    return;
                }                //只有在边框样式为FixedSingle时自定义边框样式才有效 
                if (this.BorderStyle == BorderStyle.FixedSingle)
                {
                    //边框Width为1个像素 
                    System.Drawing.Pen pen = new Pen(this._BorderColor, 1); ;                    //绘制边框 
                    System.Drawing.Graphics g = Graphics.FromHdc(hDC);
                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
                    g.DrawRectangle(pen, 0, 0, this.Width - 1, this.Height - 1);
                    pen.Dispose();
                }
            }        }        #endregion

Answer 5

内容太长了，继续。        #region  OnChar Method (Overridable)        //Method of call when character string is transmitted to client area 
        protected virtual void OnChar(KeyPressEventArgs e)
        {            if (char.IsControl(e.KeyChar))
            {
                switch (e.KeyChar)
                {
                    case (char)13:
                    case (char)9:
                        if (this.MaxValue != 0)
                        {
                            if (Convert.ToInt32(this.Text) > this.MaxValue)
                            {
                                this.SelectAll();
                                e.Handled = true;
                                return;
                            }                        }
                        if (this.MinValue != 0)
                        {
                            if (Convert.ToInt32(this.Text) < this.MinValue)
                            {
                                this.SelectAll();
                                e.Handled = true;
                                return;
                            }                        }                        break;                }                return;            }            if (!HasPermitChars(e.KeyChar, this.PermitChars))
            {
                e.Handled = true;
                return;
            }            switch (e.KeyChar)
            {
                case (char)46:
                    //CASE [ . ] 
                    try
                    {
                        if (DecimalLength == 0)
                        {
                            e.Handled = true;
                            return;
                        }                        if (Text.Length == 0)
                        {
                            return;
                        }                        int decimalPlace = Text.IndexOf(e.KeyChar);
                        if (decimalPlace > 0)
                        {
                            e.Handled = true;
                            return;
                        }
                    }                    catch
                    {                    }                    break;                case (char)43:
                case (char)45:
                    //CASE [ + or - ] 
                    try
                    {
                        if (Text.Length == 0)
                        {
                            return;
                        }                        int plusPlace = Text.IndexOf((char)43);
                        int minusPlace = Text.IndexOf((char)45);                        if (plusPlace >= 0 | minusPlace >= 0)
                        {
                            e.Handled = true;
                            return;
                        }                        if (SelectionStart >= 1)
                        {
                            e.Handled = true;
                            return;
                        }
                    }                    catch
                    {                    }                    break;                default:
                    //CASE [ NUMBER ] 
                    if (DecimalLength == 0)
                    {
                        return;
                    }
                    if (Text.Length == 0)
                    {
                        return;
                    }
                    int dStart = Text.IndexOf((char)46);
                    if (dStart >= 0)
                    {
                        if (SelectionStart <= dStart)
                        {
                            return;
                        }
                        else
                        {
                            int dLen = (Text.Length + 1) - (dStart + 1);
                            if (dLen > _DecimalLength)
                            {
                                e.Handled = true;
                                return;
                            }
                        }                    }                    break;            }        }        #endregion        #region  OnPaste Method (Overridable)        //Method of call when Paste it 
        protected virtual void OnPaste(System.EventArgs e)
        {
            string stString = Clipboard.GetDataObject().GetData(System.Windows.Forms.DataFormats.Text).ToString();            if ((stString != null))
            {
                SelectedText = GetPermitedString(stString, PermitChars);
            }        }        #endregion        #region  [S] HasPermitChars Method        //The value in which it is shown whether it is a permitted character is returned. 
        private static bool HasPermitChars(char chTarget, char[] chPermits)
        {
            foreach (char ch in chPermits)
            {
                if (chTarget == ch)
                {
                    return true;
                }
            }
            return false;        }        #endregion        #region  [S] GetPermitedString Method        //Only the permitted character is connected and returned 
        private static string GetPermitedString(string stTarget, char[] chPermits)
        {
            string stReturn = string.Empty;            foreach (char chTarget in stTarget)
            {
                if (HasPermitChars(chTarget, chPermits))
                {
                    return stReturn;
                }            }            return stReturn;
        }        #endregion
    }}

Answer 6

给Textbox添加 KeyPress 事件
代码如下，即可实现Textbox.text中让输入的信息只能是数字
 private void txtNumber_KeyPress(object sender, KeyPressEventArgs e)
        {
            e.Handled = e.KeyChar<'0'||e.KeyChar>'9';
            if(e.KeyChar==(Char)8)
            {
                e.Handled = false;
            }        }