如何防止用户在TextBox中放入特殊字符 [英] How can I Prevent users to put special characters in a TextBox

问题描述

我想阻止用户在TextBox中输入，等特殊字符。

Textbox是一个只能接受名字的搜索框（仅限a到z和0-9）。



我想使用自定义验证器，但不知道在C＃代码中放什么。



如何我可以吗？





*********

< asp：CustomValidator ID =   CustomValidator1 runat =   server 
 ControlToValidate =   SearchTextBox 
 ErrorMessage =  不允许使用特殊字符 
 onservervalidate =   CustomValidator1_ServerValidate /> 

************

<前lang =cs> 受保护 void ServerValidate（ object sender，ServerValidateEventArgs e）
{
// 这里需要代码。
}

谢谢..

解决方案

对于文本框中的任何字母数字要求，我使用内置验证器，使用ajaxtoolkit扩展窗口。

< asp：TextBox ID =txtIDrunat =serverWidth =50％MaxLength = 10 >< / ASP：文本框> 
< asp：Label ID =lblRequiredFieldIndicator0runat =serverFont-Bold =TrueForeColor =RedText =*>< / asp：Label> 
< asp：RegularExpressionValidator ID =regExIDForeColor =Redrunat =serverHeight =24pxWidth =192pxControlToValidate =txtIDDisplay =NoneValidationExpression =^ [0 -9a-zA-Z  - ] + 

ErrorMessage =仅字母数字字符>< / asp：RegularExpressionValidator>
< ajaxToolkit：ValidatorCalloutExtender runat =ServerID =vceRegExIDTargetControlID =regExIDHighlightCssClass =validatorCalloutHighlightWidth =250px/>
< asp：RequiredFieldValidator runat =serverID =reqIDControlToValidate =txtIDDisplay =NoneErrorMessage =< b>必填字段缺失< / b>< br />否特殊字符允许。 />
< ajaxToolkit：ValidatorCalloutExtender runat =ServerID =vceIDTargetControlID =reqIDHighlightCssClass =validatorCalloutHighlightWidth =250px/>

我不明白你的C＃问题。对于任何字符 ch 你，可以轻松检查它是否是某些坏字符的元素，或者可以在一组好字符中找到它：

  if （System.Char.IsLetter（ch）| | System.Char.IsDigit（ch）） //   ... good one  
 
  //  或 
 
  string  badCharacters =  。; *？^&;  //  无论 
 如果 （badCharacters.Contains（ch）） //   ... bad one  
 
  //  或者，您可以通过拉丁语和数字来限制好字符......  

但是，如果你想在文本框中限制字符输入，你最好不要在C＃中这样做，因为每一个输入你将有一个回发，这将减慢超出任何可容忍的东西。然后你需要根据字符代码点过滤掉按键的JavaScript。这也很容易。

-SA

I want to prevent users from entering Special characters like " ,' etc in a TextBox.
Textbox is a search box which can accept names only (a to z and 0-9 only).

I want to use a Custom validator but no idea what to put in C# code.

How can I do it?


*********

<asp:CustomValidator ID="CustomValidator1" runat="server"
                    ControlToValidate="SearchTextBox"
                    ErrorMessage="Special Characters are not allowed"
                    onservervalidate="CustomValidator1_ServerValidate" />

************

protected void ServerValidate(object sender, ServerValidateEventArgs e)
{
   //need code here.
}

Thanks..

解决方案

For any alphanumeric requirements in a textbox I use the built in validator with an extention for popup window using the ajaxtoolkit.

<asp:TextBox ID="txtID" runat="server" Width="50%" MaxLength="10"></asp:TextBox>
<asp:Label ID="lblRequiredFieldIndicator0" runat="server" Font-Bold="True" ForeColor="Red" Text="*"></asp:Label>
<asp:RegularExpressionValidator ID="regExID" ForeColor="Red" runat="server" Height="24px" Width="192px" ControlToValidate="txtID" Display="None" ValidationExpression="^[0-9a-zA-Z-]+

" ErrorMessage="Only Alphanumeric characters"></asp:RegularExpressionValidator> <ajaxToolkit:ValidatorCalloutExtender runat="Server" ID="vceRegExID" TargetControlID="regExID" HighlightCssClass="validatorCalloutHighlight" Width="250px" /> <asp:RequiredFieldValidator runat="server" ID="reqID" ControlToValidate="txtID" Display="None" ErrorMessage="<b>Required Field Missing</b><br />No Special Characters allowed." /> <ajaxToolkit:ValidatorCalloutExtender runat="Server" ID="vceID" TargetControlID="reqID" HighlightCssClass="validatorCalloutHighlight" Width="250px" />

I don't understand your problem with C#. For any character ch you, can easily check if it is an element of some set of "bad" characters, or it can be found in a set of the "good" characters:

if (System.Char.IsLetter(ch) || System.Char.IsDigit(ch)) //... good one

// or

string badCharacters = ".;*?^&"; // whatever
if (badCharacters.Contains(ch)) //... bad one

// or, you can limit "good" characters by just Latin and digits...

However, if you want to constraint the character input in, say, text box, you should better not do it in C#, because on every input you will have a postback which would slow down things beyond anything tolerable. Then you need to have a JavaScript filtering out key presses based on the character code point. This is easy enough, too.

—SA

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