C# TextChanged事件（WPF Textbox）的奇怪错误

我有一个文本框，我试图用两种方式限制它：

1-我只允许数值，不允许小数

---

2-我只想接受您的代码不符合第一个条件的数字，因为

string.IsNullOrEmpty(textBoxWorkflowCount.Text) 

计算结果为true，因此将转到“else”并显示消息

if (string.IsNullOrEmpty(textBoxWorkflowCount.Text) || Convert.ToInt32(textBoxWorkflowCount.Text) <= 35) e.Handled = true; 

if（string.IsNullOrEmpty（textBoxWorkflowCount.Text）| Convert.ToInt32（textBoxWorkflowCount.Text）几个月前，我发布了关于TextBox（Windows Phone 7.5平台）行为的帖子，其中一个是TextBoxInputRegexFilterBehavior，它允许您过滤输入文本。因此，如果您熟悉行为的工作方式，可以使用此代码

using System.Text.RegularExpressions;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Interactivity;

/// <summary>
/// UI behavior for <see cref="TextBox"/> to filter input text with special RegularExpression.
/// </summary>
public class TextBoxInputRegexFilterBehavior : Behavior<TextBox>
{
    private Regex regex;

    private string originalText;
    private int originalSelectionStart;
    private int originalSelectionLength;

    /// <summary>
    /// Gets or sets RegularExpression.
    /// </summary>
    public string RegularExpression 
    {
        get
        {
            return this.regex.ToString();
        } 

        set 
        {
            if (string.IsNullOrEmpty(value))
            {
                this.regex = null;
            }
            else
            {
                this.regex = new Regex(value);
            }
        } 
    }

    /// <inheritdoc/>
    protected override void OnAttached()
    {
        base.OnAttached();

        this.AssociatedObject.TextInputStart += this.AssociatedObjectTextInputStart;
        this.AssociatedObject.TextChanged += this.AssociatedObjectTextChanged;
    }

    /// <inheritdoc/>
    protected override void OnDetaching()
    {
        base.OnDetaching();

        this.AssociatedObject.TextInputStart -= this.AssociatedObjectTextInputStart;
        this.AssociatedObject.TextChanged -= this.AssociatedObjectTextChanged;
    }

    private void AssociatedObjectTextChanged(object sender, TextChangedEventArgs e)
    {
        if (this.originalText != null)
        {
            string text = this.originalText;
            this.originalText = null;
            this.AssociatedObject.Text = text;
            this.AssociatedObject.Select(this.originalSelectionStart, this.originalSelectionLength);
        }
    }

    private void AssociatedObjectTextInputStart(object sender, TextCompositionEventArgs e)
    {
        if (this.regex != null && e.Text != null && !(e.Text.Length == 1 && char.IsControl(e.Text[0])))
        {
            if (!this.regex.IsMatch(e.Text))
            {
                this.originalText = this.AssociatedObject.Text;
                this.originalSelectionStart = this.AssociatedObject.SelectionStart;
                this.originalSelectionLength = this.AssociatedObject.SelectionLength;
            }
        }
    }
}

使用System.Text.regular表达式；
使用System.Windows.Controls；
使用System.Windows.Input；
使用System.Windows.Interactive；
/// 
///用于筛选具有特殊RegularExpression的输入文本的UI行为。
/// 
公共类TextBoxInputRegexFilterBehavior:行为
{
私人正则表达式正则表达式；
私有字符串源文本；
私人int原始选择启动；
private int originalSelectionLength；
/// 
///获取或设置正则表达式。
/// 
公共字符串正则表达式
{
得到
{
返回这个.regex.ToString（）；
} 
设置
{
if（string.IsNullOrEmpty（value））
{
this.regex=null；
}
其他的
{
this.regex=新的regex（值）；
}
} 
}
/// 
受保护的覆盖无效附加（）
{
base.onatached（）；
this.AssociatedObject.TextInputStart+=this.AssociatedObjectTextInputStart；
this.AssociatedObject.TextChanged+=this.AssociatedObjectTextChanged；
}
/// 
附加时受保护的覆盖无效（）
{
base.OnDetaching（）；
this.AssociatedObject.TextInputStart-=this.AssociatedObjectTextInputStart；
this.AssociatedObject.TextChanged-=this.AssociatedObjectTextChanged；
}
与ObjectTextChanged关联的私有void（对象发送者，TextChangedEventArgs e）
{
如果（this.originalText！=null）
{
字符串文本=this.originalText；
this.originalText=null；
this.AssociatedObject.Text=文本；
this.AssociatedObject.Select（this.originalSelectionStart，this.originalSelectionLength）；
}
}
私有void AssociatedObjectTextInputStart（对象发送者，TextCompositionEventArgs e）
{
如果（this.regex！=null&&e.Text！=null&&！（e.Text.Length==1&&char.IsControl（e.Text[0]））
{
如果（！this.regex.IsMatch（e.Text））
{
this.originalText=this.AssociatedObject.Text；
this.originalSelectionStart=this.associated object.SelectionStart；
this.originalSelectionLength=this.AssociatedObject.SelectionLength；
}
}
}
}

因此，通过这种行为，您可以编写简单的正则表达式来过滤用户输入，如RegularExpression=“（3[0-5]）|（[0-2]？[0-9]）”
哇，这太棒了-一定会用到。谢谢！
using System.Text.RegularExpressions;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Interactivity;

/// <summary>
/// UI behavior for <see cref="TextBox"/> to filter input text with special RegularExpression.
/// </summary>
public class TextBoxInputRegexFilterBehavior : Behavior<TextBox>
{
    private Regex regex;

    private string originalText;
    private int originalSelectionStart;
    private int originalSelectionLength;

    /// <summary>
    /// Gets or sets RegularExpression.
    /// </summary>
    public string RegularExpression 
    {
        get
        {
            return this.regex.ToString();
        } 

        set 
        {
            if (string.IsNullOrEmpty(value))
            {
                this.regex = null;
            }
            else
            {
                this.regex = new Regex(value);
            }
        } 
    }

    /// <inheritdoc/>
    protected override void OnAttached()
    {
        base.OnAttached();

        this.AssociatedObject.TextInputStart += this.AssociatedObjectTextInputStart;
        this.AssociatedObject.TextChanged += this.AssociatedObjectTextChanged;
    }

    /// <inheritdoc/>
    protected override void OnDetaching()
    {
        base.OnDetaching();

        this.AssociatedObject.TextInputStart -= this.AssociatedObjectTextInputStart;
        this.AssociatedObject.TextChanged -= this.AssociatedObjectTextChanged;
    }

    private void AssociatedObjectTextChanged(object sender, TextChangedEventArgs e)
    {
        if (this.originalText != null)
        {
            string text = this.originalText;
            this.originalText = null;
            this.AssociatedObject.Text = text;
            this.AssociatedObject.Select(this.originalSelectionStart, this.originalSelectionLength);
        }
    }

    private void AssociatedObjectTextInputStart(object sender, TextCompositionEventArgs e)
    {
        if (this.regex != null && e.Text != null && !(e.Text.Length == 1 && char.IsControl(e.Text[0])))
        {
            if (!this.regex.IsMatch(e.Text))
            {
                this.originalText = this.AssociatedObject.Text;
                this.originalSelectionStart = this.AssociatedObject.SelectionStart;
                this.originalSelectionLength = this.AssociatedObject.SelectionLength;
            }
        }
    }
}