blocks|key|890617|text|这对我来说就够了。我没有保留MultiLine属性。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|890618|<asp:TextBox+ID="txtBodySMS"+runat="server"+Rows="10"+MaxLength="2"+Width="100%25"></asp:TextBox>|code-block|syntax|javascript|890619|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This did it for me. I did not keep the MultiLine property.

<pre><code>&lt;asp:TextBox ID="txtBodySMS" runat="server" Rows="10" MaxLength="2" Width="100%"&gt;&lt;/asp:TextBox&gt;
</code></pre>

blocks|key|673719|text|MaxLength="Int32“|type|unstyled|depth|inlineStyleRanges|entityRanges|data|673720|<asp:TextBox+ID="txtBodySMS"+runat="server"+Rows="10"+MaxLength="220"+++++++++++++++++++++++++
+++++++++++TextMode="MultiLine"+Width="100%25"></asp:TextBox>|code-block|syntax|javascript|673721|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

MaxLength="Int32"

<pre><code>&lt;asp:TextBox ID="txtBodySMS" runat="server" Rows="10" MaxLength="220" 
 TextMode="MultiLine" Width="100%"&gt;&lt;/asp:TextBox&gt;
</code></pre>

blocks|key|890765|text|最大字符长度验证(最多8个字符)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|890766|<asp:TextBox+ID="TextBox1"+runat="server"></asp:TextBox>
<asp:RegularExpressionValidator+Display+=+"Dynamic"+ControlToValidate+=+"TextBox1"+ID="RegularExpressionValidator1"+ValidationExpression+=+"%5E[\s\S]{0,8}$"+runat="server"+ErrorMessage="Maximum+8+characters+allowed."></asp:RegularExpressionValidator>|code-block|syntax|javascript|890767|最小字符长度验证(至少需要8个字符)|890768|<asp:TextBox+ID="TextBox2"+runat="server"></asp:TextBox>
<asp:RegularExpressionValidator+Display+=+"Dynamic"+ControlToValidate+=+"TextBox2"+ID="RegularExpressionValidator2"+ValidationExpression+=+"%5E[\s\S]{8,}$"+runat="server"+ErrorMessage="Minimum+8+characters+required."></asp:RegularExpressionValidator>|890769|最小和最大字符长度验证(需要最少5个字符，最多8个字符)|890770|<asp:TextBox+ID="TextBox3"+runat="server"></asp:TextBox>
<asp:RegularExpressionValidator+Display+=+"Dynamic"+ControlToValidate+=+"TextBox3"+ID="RegularExpressionValidator3"+ValidationExpression+=+"%5E[\s\S]{5,8}$"+runat="server"+ErrorMessage="Minimum+5+and+Maximum+8+characters+required."></asp:RegularExpressionValidator>|890771|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Maximum character length Validation (Maximum 8 characters allowed)

<pre><code>&lt;asp:TextBox ID="TextBox1" runat="server"&gt;&lt;/asp:TextBox&gt;
&lt;asp:RegularExpressionValidator Display = "Dynamic" ControlToValidate = "TextBox1" ID="RegularExpressionValidator1" ValidationExpression = "^[\s\S]{0,8}$" runat="server" ErrorMessage="Maximum 8 characters allowed."&gt;&lt;/asp:RegularExpressionValidator&gt;
</code></pre>

Minimum character length Validation (Minimum 8 characters required)

<pre><code>&lt;asp:TextBox ID="TextBox2" runat="server"&gt;&lt;/asp:TextBox&gt;
&lt;asp:RegularExpressionValidator Display = "Dynamic" ControlToValidate = "TextBox2" ID="RegularExpressionValidator2" ValidationExpression = "^[\s\S]{8,}$" runat="server" ErrorMessage="Minimum 8 characters required."&gt;&lt;/asp:RegularExpressionValidator&gt;
</code></pre>

Minimum and Maximum character length Validation (Minimum 5 and Maximum 8 characters required)

<pre><code>&lt;asp:TextBox ID="TextBox3" runat="server"&gt;&lt;/asp:TextBox&gt;
&lt;asp:RegularExpressionValidator Display = "Dynamic" ControlToValidate = "TextBox3" ID="RegularExpressionValidator3" ValidationExpression = "^[\s\S]{5,8}$" runat="server" ErrorMessage="Minimum 5 and Maximum 8 characters required."&gt;&lt;/asp:RegularExpressionValidator&gt;
</code></pre>

blocks|key|673964|text|AFAIK+maxlength从未与"multiline“模式一起工作过。因此，我建议使用一些客户端js/jquery和服务器端来解决这个问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|673965|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

AFAIK maxlength has never worked in conjunction with the "multiline" mode. Therefore I would suggest some client-side js/jquery and server-side to get around the problem.

blocks|key|674169|text|只需在.cs页面加载中键入两行以下即可|type|unstyled|depth|inlineStyleRanges|entityRanges|data|674170|textbox1.Attributes.Remove("MaxLength");
textbox1.Attributes.Add("MaxLength",+"30");|code-block|syntax|javascript|674171|希望它能有所帮助！|674172|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Just type below two line in .cs page load 

<pre><code>textbox1.Attributes.Remove("MaxLength");
textbox1.Attributes.Add("MaxLength", "30");
</code></pre>

Hope it will help !

blocks|key|890499|text|将MaxLength属性设置为字符数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|890500|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Set the MaxLength attribute to the number of characters.

blocks|key|890556|text|你正在寻找MaxLength:+Look+here|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|890557|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.textbox.maxlength.aspx^0|L|4|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

You are looking for MaxLength: Look <a href="http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.textbox.maxlength.aspx" rel="nofollow">here</a>

blocks|key|673864|text|您是否尝试过在TextBox上设置MaxLength属性？对于Reference|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|673865|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.textbox.maxlength.aspx^0|V|9|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Have you tried setting the MaxLength Property on the TextBox? for <a href="http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.textbox.maxlength.aspx" rel="nofollow">Reference</a>

blocks|key|890694|text|为文本框添加FliterTextBoxExtender类型的扩展器|type|unstyled|depth|inlineStyleRanges|entityRanges|data|890695|它应该看起来像这样|890696|<asp:TextBox+ID="TxtCellular"+runat="server"></asp:TextBox>
<asp:FilteredTextBoxExtender+ID="TxtCellular_FilteredTextBoxExtender"+
++++++++++++++++++++runat="server"+Enabled="True"+TargetControlID="TxtCellular"+FilterType="Numbers">
</asp:FilteredTextBoxExtender>|code-block|syntax|javascript|890697|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Add an extender of type FliterTextBoxExtender for your text box 
it should appear like that

<pre><code>&lt;asp:TextBox ID="TxtCellular" runat="server"&gt;&lt;/asp:TextBox&gt;
&lt;asp:FilteredTextBoxExtender ID="TxtCellular_FilteredTextBoxExtender" 
 runat="server" Enabled="True" TargetControlID="TxtCellular" FilterType="Numbers"&gt;
&lt;/asp:FilteredTextBoxExtender&gt;
</code></pre>

blocks|key|674125|text|值得注意的是，单独使用MaxLength+(不需要添加其他属性，就像其他答案一样)仅适用于.NET+Framework4.5及更高版本中的项目。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|674126|我使用的是4.5，它适用于我的项目|674127|<asp:TextBox+ID="txtSample"+MaxLength="3"+runat="server"/>|code-block|syntax|javascript|674128|TextBox.MaxLength+Property+(MSDN+Documentation)|674129|entityMap|0|LINK|mutability|MUTABLE|url|https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.textbox.maxlength(v=vs.110).aspx^0|B|9|0|0|0|0|1B|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@]|D|@$9|12|A|13|1|14]]|E|$]]|$1|O|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

It is important to note that using <code>MaxLength</code> alone (with no other properties to add, just like the other answers) works ONLY for projects in .NET Framework 4.5 and above.

I'm using 4.5, and it worked for my project

<pre><code>&lt;asp:TextBox ID="txtSample" MaxLength="3" runat="server"/&gt;
</code></pre>

<a href="https://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.textbox.maxlength(v=vs.110).aspx" rel="nofollow">TextBox.MaxLength Property (MSDN Documentation)</a>

blocks|key|674209|text|可以设置textbox的MaxLength属性似乎是ASP.NET设计中的一个奇怪的疏忽(不考虑textbox的异常)，但是在没有显式添加验证器的情况下，似乎没有办法在服务器端实施这一限制。如果您有很多字段，并且只想确保没有人通过注入自己的POST数据来降低表单的限制，那么这就很麻烦了。所以我写了这篇文章，这看起来很管用--显然你可能不想强迫Response.End|type|unstyled|depth|inlineStyleRanges|entityRanges|data|674210|Protected+Sub+Page_Load(sender+As+Object,+e+As+System.EventArgs)+Handles+Me.Load

++++++++Dim+colControls+As+Collection+=+New+Collection
++++++++getControlList(colControls,+Me)
++++++++For+Each+ctlNextPlease+As+Control+In+colControls
++++++++++++If+TypeOf+(ctlNextPlease)+Is+TextBox+Then
++++++++++++++++Dim+ctlTextBox+As+TextBox+=+ctlNextPlease
++++++++++++++++If+Len(Request(ctlTextBox.ID))+>+ctlTextBox.MaxLength+Then
++++++++++++++++++++Response.Write("The+value+"+&+Request(ctlTextBox.ID)+&+"+submitted+for+"+&+ctlTextBox.ID+&+"+exceeds+the+permitted+maximum+length+("+&+ctlTextBox.MaxLength+&+")+for+that+value")
++++++++++++++++++++Response.End()
++++++++++++++++End+If
++++++++++++End+If
++++++++Next
...
End+Sub

Public+Shared+Sub+getControlList(ByRef+colControls+As+Collection,+ByVal+rootControl+As+Control)
++colControls.Add(rootControl)
++If+rootControl.Controls.Count+>+0+Then
++++For+Each+controlToSearch+As+Control+In+rootControl.Controls
++++++getControlList(colControls,+controlToSearch)
++++Next
++End+If
End+Sub|code-block|syntax|javascript|674211|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

It seems to be a curious oversight in the design of ASP.NET (leaving aside the anomaly with textareas) that you can set the MaxLength property of a textbox but there seems to be no way provided to enforce this limit server-side without explicitly adding a validator. That's a nuisance if you have lots of fields and just want to be sure that no-one is subventing the limits of the form by injecting their own POST data. So I wrote this, which seems to do the trick - obviously you might not want to force Response.End

<pre><code>Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load

 Dim colControls As Collection = New Collection
 getControlList(colControls, Me)
 For Each ctlNextPlease As Control In colControls
 If TypeOf (ctlNextPlease) Is TextBox Then
 Dim ctlTextBox As TextBox = ctlNextPlease
 If Len(Request(ctlTextBox.ID)) &gt; ctlTextBox.MaxLength Then
 Response.Write("The value &lt;i&gt;" &amp; Request(ctlTextBox.ID) &amp; "&lt;/i&gt; submitted for &lt;b&gt;" &amp; ctlTextBox.ID &amp; "&lt;/b&gt; exceeds the permitted maximum length (" &amp; ctlTextBox.MaxLength &amp; ") for that value")
 Response.End()
 End If
 End If
 Next
...
End Sub

Public Shared Sub getControlList(ByRef colControls As Collection, ByVal rootControl As Control)
 colControls.Add(rootControl)
 If rootControl.Controls.Count &gt; 0 Then
 For Each controlToSearch As Control In rootControl.Controls
 getControlList(colControls, controlToSearch)
 Next
 End If
End Sub
</code></pre>

blocks|key|674217|text|<asp:TextBox+ID="txtBodySMS"+runat="server"+Rows="10"+MaxLength="220"+
++++TextMode="MultiLine"+Width="100%25">
</asp:TextBox>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|674218|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre class="lang-xml prettyprint-override"><code>&lt;asp:TextBox ID=&quot;txtBodySMS&quot; runat=&quot;server&quot; Rows=&quot;10&quot; MaxLength=&quot;220&quot; 
 TextMode=&quot;MultiLine&quot; Width=&quot;100%&quot;&gt;
&lt;/asp:TextBox&gt;
</code></pre>

<pre><code>&lt;asp:TextBox ID="txtBodySMS" runat="server" Rows="10" 
 TextMode="MultiLine" Width="100%"&gt;&lt;/asp:TextBox&gt;
</code></pre>

This is my text box. How do I limit the number of characters a user can type inside it?

How to limit the number of characters allowed in a textbox?

服务器

<asp:TextBox ID="txtBodySMS" runat="server" Rows="10" TextMode="MultiLine" Width="100%"></asp:TextBox>这是我的文本框。如何限制用户可以在其中键入的字符数？

问如何限制文本框中允许的字符数？
EN

回答 12

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问如何限制文本框中允许的字符数？EN

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问如何限制文本框中允许的字符数？
EN