我有一个windows窗体应用程序与一个文本框控件，我想只接受整数值。在过去，我通过重载KeyPress事件并删除不符合规范的字符来进行这种验证。我已经看了MaskedTextBox控件，但我想一个更通用的解决方案，可以与也许正则表达式，或依赖于其他控件的值。
理想情况下，按下非数字字符要么不产生结果，要么立即向用户提供关于无效字符的反馈。
当前回答
看一下WinForm中的输入处理
我已经发布了我的解决方案，在文本框上使用ProcessCmdKey和OnKeyPress事件。注释向您展示了如何使用Regex来验证键按和适当地阻止/允许。
其他回答
int Number;
bool isNumber;
isNumber = int32.TryPase(textbox1.text, out Number);
if (!isNumber)
{
(code if not an integer);
}
else
{
(code if an integer);
}
我已经为各种验证创建了一个可重用的文本框扩展类，并考虑共享它。
您所需要做的就是引发一个TextChange事件，然后调用Validate方法。它是这样的:
private void tbxAmount_TextChanged(object sender, EventArgs e)
{
tbxAmount.Validate(TextValidator.ValidationType.Amount);
}
下面是扩展类:
public static class TextValidator
{
public enum ValidationType
{
Amount,
Integer
}
/// <summary>
/// Validate a textbox on text change.
/// </summary>
/// <param name="tbx"></param>
/// <param name="validationType"></param>
public static void Validate(this TextBox tbx, ValidationType validationType)
{
PerformValidation(tbx, validationType);
tbx.Select(tbx.Text.Length, 0);
}
private static void PerformValidation(this TextBox tbx, ValidationType validationType)
{
char[] enteredString = tbx.Text.ToCharArray();
switch (validationType)
{
case ValidationType.Amount:
tbx.Text = AmountValidation(enteredString);
break;
case ValidationType.Integer:
tbx.Text = IntegerValidation(enteredString);
break;
default:
break;
}
tbx.SelectionStart = tbx.Text.Length;
}
private static string AmountValidation(char[] enteredString)
{
string actualString = string.Empty;
int count = 0;
foreach (char c in enteredString.AsEnumerable())
{
if (count >= 1 && c == '.')
{ actualString.Replace(c, ' '); actualString.Trim(); }
else
{
if (Char.IsDigit(c))
{
actualString = actualString + c;
}
if (c == '.')
{
actualString = actualString + c; count++;
}
else
{
actualString.Replace(c, ' ');
actualString.Trim();
}
}
}
return actualString;
}
private static string IntegerValidation(char[] enteredString)
{
string actualString = string.Empty;
foreach (char c in enteredString.AsEnumerable())
{
if (Char.IsDigit(c))
{
actualString = actualString + c;
}
else
{
actualString.Replace(c, ' ');
actualString.Trim();
}
}
return actualString;
}
}
你可以在这里找到完整的代码
只是因为在一条线上做事情总是更有趣……
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
e.Handled = !char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar);
}
注意:这并不阻止用户复制/粘贴到此文本框。这并不是清除数据的安全方法。
似乎目前对这个问题的许多答案都是手动解析输入文本。如果你正在寻找一个特定的内置数字类型(例如int或double)，为什么不只是将工作委托给该类型的TryParse方法?例如:
public class IntTextBox : TextBox
{
string PreviousText = "";
int BackingResult;
public IntTextBox()
{
TextChanged += IntTextBox_TextChanged;
}
public bool HasResult { get; private set; }
public int Result
{
get
{
return HasResult ? BackingResult : default(int);
}
}
void IntTextBox_TextChanged(object sender, EventArgs e)
{
HasResult = int.TryParse(Text, out BackingResult);
if (HasResult || string.IsNullOrEmpty(Text))
{
// Commit
PreviousText = Text;
}
else
{
// Revert
var changeOffset = Text.Length - PreviousText.Length;
var previousSelectionStart =
Math.Max(0, SelectionStart - changeOffset);
Text = PreviousText;
SelectionStart = previousSelectionStart;
}
}
}
如果你想要更通用但仍然兼容Visual Studio的设计器:
public class ParsableTextBox : TextBox
{
TryParser BackingTryParse;
string PreviousText = "";
object BackingResult;
public ParsableTextBox()
: this(null)
{
}
public ParsableTextBox(TryParser tryParse)
{
TryParse = tryParse;
TextChanged += ParsableTextBox_TextChanged;
}
public delegate bool TryParser(string text, out object result);
public TryParser TryParse
{
set
{
Enabled = !(ReadOnly = value == null);
BackingTryParse = value;
}
}
public bool HasResult { get; private set; }
public object Result
{
get
{
return GetResult<object>();
}
}
public T GetResult<T>()
{
return HasResult ? (T)BackingResult : default(T);
}
void ParsableTextBox_TextChanged(object sender, EventArgs e)
{
if (BackingTryParse != null)
{
HasResult = BackingTryParse(Text, out BackingResult);
}
if (HasResult || string.IsNullOrEmpty(Text))
{
// Commit
PreviousText = Text;
}
else
{
// Revert
var changeOffset = Text.Length - PreviousText.Length;
var previousSelectionStart =
Math.Max(0, SelectionStart - changeOffset);
Text = PreviousText;
SelectionStart = previousSelectionStart;
}
}
}
最后，如果你想要完全通用的东西，不关心Designer支持:
public class ParsableTextBox<T> : TextBox
{
TryParser BackingTryParse;
string PreviousText;
T BackingResult;
public ParsableTextBox()
: this(null)
{
}
public ParsableTextBox(TryParser tryParse)
{
TryParse = tryParse;
TextChanged += ParsableTextBox_TextChanged;
}
public delegate bool TryParser(string text, out T result);
public TryParser TryParse
{
set
{
Enabled = !(ReadOnly = value == null);
BackingTryParse = value;
}
}
public bool HasResult { get; private set; }
public T Result
{
get
{
return HasResult ? BackingResult : default(T);
}
}
void ParsableTextBox_TextChanged(object sender, EventArgs e)
{
if (BackingTryParse != null)
{
HasResult = BackingTryParse(Text, out BackingResult);
}
if (HasResult || string.IsNullOrEmpty(Text))
{
// Commit
PreviousText = Text;
}
else
{
// Revert
var changeOffset = Text.Length - PreviousText.Length;
var previousSelectionStart =
Math.Max(0, SelectionStart - changeOffset);
Text = PreviousText;
SelectionStart = previousSelectionStart;
}
}
}
这是用.NET 5/Core来实现的一种很好很短的方法
private void textBox1_KeyDown(object sender, KeyEventArgs e) {
if (e.KeyData != Keys.Back)
e.SuppressKeyPress = !int.TryParse(Convert.ToString((char) e.KeyData), out int _);
}
编辑:增加了退格键的支持
