在 C# 中限制文本框十进制输入的最佳方法 [英] Best way to limit textbox decimal input in c#
本文介绍了在 C# 中限制文本框十进制输入的最佳方法的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
如何制作一个只能输入12.00或1231231.00或123123之类的数字的文本框
How can I make a textbox in which can be only typed a number like 12.00 or 1231231.00 or 123123
我已经做了很长一段时间，我正在寻找最好和最快的方法.
I've done this in a very long way and I'm looking for the best and fastest way.
此外，小数点分隔符必须是特定于文化的.:
Also the decimal separator must be culture specific.:
Application.CurrentCulture.NumberFormat.NumberDecimalSeparator
推荐答案
这是一个相当简单的操作.您需要过滤掉不想要的键，然后执行一些额外的检查.
That's a fairly straightforward operation. You'll need to filter the keys that you don't want out and then perform some additional checks.
在文本框的KeyDown事件中添加如下代码:
Add the following code to the KeyDown event of the textbox:
private void TextBox1_KeyDown(object sender,
System.Windows.Forms.KeyEventArgs e)
{
switch (e.KeyCode) {
case Keys.D0:
case Keys.D1:
case Keys.D2:
case Keys.D3:
case Keys.D4:
case Keys.D5:
case Keys.D6:
case Keys.D7:
case Keys.D8:
case Keys.D9:
case Keys.NumPad0:
case Keys.NumPad1:
case Keys.NumPad2:
case Keys.NumPad3:
case Keys.NumPad4:
case Keys.NumPad5:
case Keys.NumPad6:
case Keys.NumPad7:
case Keys.NumPad8:
case Keys.NumPad9:
//allow numbers only when no modifiers are active
if (e.Control || e.Alt || e.Shift) {
//suppress numbers with modifiers
e.SuppressKeyPress = true;
e.Handled = true;
Interaction.Beep();
}
break;
case (Keys)110:
case Keys.OemPeriod:
if (!((TextBox)sender).Text.Contains(".")) {
//allow period key if there is no '.'
//in the text and no modifiers are active
if (e.Control || e.Alt || e.Shift) {
//suppress numbers with modifiers
e.SuppressKeyPress = true;
e.Handled = true;
Interaction.Beep();
}
} else {
e.SuppressKeyPress = true;
e.Handled = true;
Interaction.Beep();
}
break;
case Keys.Subtract:
case Keys.OemMinus:
if (((TextBox)sender).SelectionStart == 0 &&
!((TextBox)sender).Text.Contains("-")) {
//allow the negative key only when the cursor
//is at the start of the textbox
//and there are no minuses in the textbox
//and no modifiers are active
if (e.Control || e.Alt || e.Shift) {
//suppress numbers with modifiers
e.SuppressKeyPress = true;
e.Handled = true;
Interaction.Beep();
}
} else {
e.SuppressKeyPress = true;
e.Handled = true;
Interaction.Beep();
}
break;
case Keys.C:
case Keys.X:
case Keys.V:
case Keys.Z:
//allow copy, cut, paste & undo by checking for
//the CTRL state.
if (e.Control == false) {
e.SuppressKeyPress = true;
e.Handled = true;
Interaction.Beep();
}
break;
case Keys.Control:
case Keys.ControlKey:
case Keys.Alt:
case Keys.Shift:
case Keys.ShiftKey:
//allow control, alt & shift
break;
case Keys.Left:
case Keys.Right:
case Keys.Up:
case Keys.Down:
case Keys.PageUp:
case Keys.PageDown:
case Keys.Home:
case Keys.End:
//allow navigation keys
break;
case Keys.Back:
case Keys.Delete:
//allow backspace & delete
break;
default:
//suppress any other key
e.SuppressKeyPress = true;
e.Handled = true;
Interaction.Beep();
break;
}
}
然后，由于用户可能会将值粘贴到文本框中，因此将以下内容添加到文本框的 Validate 事件
And then, since a user may paste values into the textbox, you add the following to the TextBox's Validate event
private void TextBox1_Validating(object sender,
System.ComponentModel.CancelEventArgs e)
{
//just in case a value was pasted,
//we'll need to validate the value
if (!Information.IsNumeric(((TextBox)sender).Text))
{
e.Cancel = true;
}
}
<小时>
我编写了一个类来为您处理各种过滤器 [其中显然包括特定于文化的十进制符号].
I wrote a class to handle a variety of filters for you [which obviously includes the culture-specific decimal symbol].
将此类添加到您的项目中
Add this class to your project
using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
public class TextBoxFilter
{
[Flags()]
public enum Filters
{
None = 0,
Text = 1,
Numbers = 2,
AlphaNumeric = Filters.Text | Filters.Numbers,
Currency = 4,
All = Filters.Text | Filters.Numbers | Filters.Currency
}
Dictionary<TextBox, Filters> _keyFilter;
Dictionary<TextBox, string> _allowedKeys;
Dictionary<TextBox, string> _invalidKeys;
Dictionary<TextBox, Windows.Forms.KeyEventArgs> keyEventArgs;
private static string DecimalMark = Application.CurrentCulture.NumberFormat.NumberDecimalSeparator;
private static string NegativeMark = Application.CurrentCulture.NumberFormat.NegativeSign;
private static string CurrencySymb = Application.CurrentCulture.NumberFormat.CurrencySymbol;
private static string CurrencyDecimal = Application.CurrentCulture.NumberFormat.CurrencyDecimalSeparator;
public TextBoxFilter()
{
_keyFilter = new Dictionary<TextBox, Filters>();
_allowedKeys = new Dictionary<TextBox, string>();
_invalidKeys = new Dictionary<TextBox, string>();
keyEventArgs = new Dictionary<TextBox, KeyEventArgs>();
}
//set & remove filter
public void SetTextBoxFilter(TextBox textBox, Filters filter)
{
SetTextBoxFilter(textBox, filter, AllowedKeys(textBox), InvalidKeys(textBox));
}
public void SetTextBoxFilter(TextBox textBox, string allowedKeys)
{
SetTextBoxFilter(textBox, Strings.Filter(textBox), allowedKeys, InvalidKeys(textBox));
}
public void SetTextBoxFilter(TextBox textBox, string allowedKeys, string invalidKeys)
{
SetTextBoxFilter(textBox, Strings.Filter(textBox), allowedKeys, invalidKeys);
}
public void SetTextBoxFilter(TextBox textBox, Filters filter, string allowedKeys, string invalidKeys)
{
if (!_keyFilter.ContainsKey(textBox)) {
//add the textbox and its filter if it does not exist in
//the collection of registered textboxes
_keyFilter.Add(textBox, filter);
_allowedKeys.Add(textBox, allowedKeys);
_invalidKeys.Add(textBox, invalidKeys);
keyEventArgs.Add(textBox, new System.Windows.Forms.KeyEventArgs(Keys.None));
//add the event handlers
textBox.KeyDown += KeyDownUp;
textBox.KeyUp += KeyDownUp;
textBox.KeyPress += KeyPress;
textBox.Validating += Validating;
textBox.Disposed += Disposed;
} else {
//change the filter of the textbox if it exists in
//the collection of registered textboxes
_keyFilter(textBox) = filter;
_allowedKeys(textBox) = allowedKeys;
_invalidKeys(textBox) = invalidKeys;
}
}
public void RemoveTextBoxFilter(TextBox textBox)
{
if (_keyFilter.ContainsKey(textBox)) {
_keyFilter.Remove(textBox);
_allowedKeys.Remove(textBox);
_invalidKeys.Remove(textBox);
keyEventArgs.Remove(textBox);
textBox.KeyDown -= KeyDownUp;
textBox.KeyUp -= KeyDownUp;
textBox.KeyPress -= KeyPress;
textBox.Validating -= Validating;
textBox.Disposed -= Disposed;
}
}
public bool ContainsTextBox(TextBox textBox)
{
return _keyFilter.ContainsKey(textBox);
}
//properties
public Filters Filter {
get {
if (ContainsTextBox(textBox)) {
return _keyFilter.Item[textBox];
} else {
return Filters.None;
}
}
set { SetTextBoxFilter(textBox, value); }
}
public string AllowedKeys {
get {
if (ContainsTextBox(textBox)) {
return _allowedKeys(textBox);
} else {
return "";
}
}
set { SetTextBoxFilter(textBox, this.Filter(textBox), value, this.InvalidKeys(textBox)); }
}
public string InvalidKeys {
get {
if (ContainsTextBox(textBox)) {
return _invalidKeys(textBox);
} else {
return "";
}
}
set { SetTextBoxFilter(textBox, this.Filter(textBox), this.AllowedKeys(textBox), value); }
}
//event handlers
private void Disposed(object sender, System.EventArgs e)
{
RemoveTextBoxFilter((TextBox)sender);
}
private void KeyDownUp(object sender, System.Windows.Forms.KeyEventArgs e)
{
//assign the modifiers
keyEventArgs((TextBox)sender) = e;
}
private void KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
//ensure key pressed is in the allowed keys
object txt = (TextBox)sender;
object c = e.KeyChar;
bool allowKey = IsValidChar(txt, c, txt.SelectionStart);
//check for backspace & Ctrl combinations if the allowKey is still false
if (allowKey == false) {
if (keyEventArgs(txt).Control) {
//control modifier goes with A, X, C, V and Z for
//Select All, Cut, Copy, Paste and Undo respectively
object key = keyEventArgs(txt).KeyCode;
allowKey = (key == Keys.A || key == Keys.X || key == Keys.C || key == Keys.V || key == Keys.Z);
} else if (keyEventArgs(txt).KeyCode == Keys.Back) {
//allow the backspace key
allowKey = true;
}
}
//disable the key if it was not valid
if (!allowKey) {
e.Handled = true;
Interaction.Beep();
}
}
private void Validating(object sender, System.ComponentModel.CancelEventArgs e)
{
object box = (TextBox)sender;
object boxFlags = _keyFilter(box);
//skip validation if the textbox allows all entries or there is no text
if (boxFlags == Filters.All | string.IsNullOrEmpty(box.Text))
return;
//otherwise check the characters entered
object txtChars = box.Text.ToCharArray;
bool isValidEntry = false;
//check each caracter for an invalid entry
for (i = 0; i <= txtChars.Length - 1; i++) {
object c = txtChars(i);
isValidEntry = IsValidChar(box, txtChars(i), i);
if (!isValidEntry) {
box.Select(i, 1);
break; // TODO: might not be correct. Was : Exit For
}
}
if (!isValidEntry)
e.Cancel = true;
if (!isValidEntry) {
Interaction.MsgBox("The text entered is invalid for the format " + boxFlags.ToString + "." + !string.IsNullOrEmpty(_allowedKeys(box)) ? Constants.vbCrLf + "Additional Allowed Keys: " + _allowedKeys(box) : "" + !string.IsNullOrEmpty(_invalidKeys(box)) ? Constants.vbCrLf + "Additional Invalid Keys: " + _invalidKeys(box) : "", MsgBoxStyle.Critical, "Invalid Entry");
}
}
private bool IsValidChar(TextBox textBox, char c, int charIndex)
{
//ensure key pressed is in the allowed keys
object pF = _keyFilter(textBox);
object aK = _allowedKeys(textBox);
object iK = _invalidKeys(textBox);
bool shouldAllow = false;
//if filter is set to all, return true unconditionally
if (pF == Filters.All)
return true;
//check preset filters
//check for text
if (EnumHasFlag(pF, Filters.Text)) {
if (!char.IsDigit(c)) {
shouldAllow = true;
} else {
//if the character is a digit, check for the number flag (AlphaNumerics)
if (EnumHasFlag(pF, Filters.Numbers)) {
shouldAllow = true;
}
}
}
//check for nubers
if (shouldAllow == false && EnumHasFlag(pF, Filters.Numbers)) {
if (char.IsDigit(c)) {
shouldAllow = true;
} else if (DecimalMark.Contains(c)) {
//allow the decimal if there is no decimal in the textbox's
//text or the selected text contains the mark
if (!textBox.Text.Substring(0, charIndex).Contains(c) || textBox.SelectedText.Contains(c)) {
shouldAllow = true;
}
} else if (NegativeMark.Contains(c) && (charIndex <= NegativeMark.IndexOf(c))) {
//allow the negative mark if we are at the start of the
//textbox
shouldAllow = true;
}
}
//check for currency
if (shouldAllow == false && EnumHasFlag(pF, Filters.Currency)) {
if (char.IsDigit(c)) {
shouldAllow = true;
} else if (CurrencyDecimal.Contains(c)) {
//allow the currency decimal mark if it does not exist in the
//textbox's text or the selected text contains the mark
if (!textBox.Text.Substring(0, charIndex).Contains(c) || textBox.SelectedText.Contains(c)) {
shouldAllow = true;
}
} else if (CurrencySymb.Contains(c) && (charIndex <= CurrencySymb.IndexOf(c))) {
//allow the currency symbol if we are in a valid position
shouldAllow = true;
}
}
//now check for extra allowed keys
if (!shouldAllow) {
shouldAllow = aK.Contains(c);
}
//and then check for extra invalid keys
if (shouldAllow && iK.Contains(c)) {
shouldAllow = false;
}
return shouldAllow;
}
[System.Diagnostics.DebuggerStepThrough()]
private bool EnumHasFlag(Enum value, Enum flag)
{
return (Convert.ToInt64(value) & Convert.ToInt64(flag)) == Convert.ToInt64(flag);
}
}
然后在您的表单中使用它，如下所示
and then use it in your form as follows
public class Form1
{
TextBoxFilter filter = new TextBoxFilter();
private void Form1_Load(object sender, System.EventArgs e)
{
filter.SetTextBoxFilter(TextBox1, TextBoxFilter.Filters.Numbers);
}
public Form1()
{
Load += Form1_Load;
}
}
这篇关于在 C# 中限制文本框十进制输入的最佳方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
