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

<asp:TextBox ID="txtBodySMS" runat="server" Rows="10"
TextMode="MultiLine" Width="100%"></asp:TextBox>

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

MaxLength="Int32"

<asp:TextBox ID="txtBodySMS" runat="server" Rows="10" MaxLength="220"
TextMode="MultiLine" Width="100%"></asp:TextBox>

Set the MaxLength attribute to the number of characters.

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.

You are looking for MaxLength: Look [here](

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Have you tried setting the MaxLength Property on the TextBox? for [Reference](

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

<asp:TextBox ID="TxtCellular" runat="server"></asp:TextBox>
<asp:FilteredTextBoxExtender ID="TxtCellular_FilteredTextBoxExtender"
runat="server" Enabled="True" TargetControlID="TxtCellular" FilterType="Numbers">
</asp:FilteredTextBoxExtender>

Maximum character length Validation (Maximum 8 characters allowed)

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



Minimum character length Validation (Minimum 8 characters required)

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



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


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

It is important to note that using `MaxLength` 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

<asp:TextBox ID="txtSample" MaxLength="3" runat="server"/>

[TextBox.MaxLength Property (MSDN Documentation)][1]


[1]:

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Just type below two line in .cs page load

textbox1.Attributes.Remove("MaxLength");
textbox1.Attributes.Add("MaxLength", "30");

Hope it will help !