Minimum and Maximum Character Length Validation using ASP.Net

Here I am explain how we can do enforce minimum and maximum character length validation in ASP.Net TextBox control using ASP.Net

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>

Minimum and Maximum character length Validation Using HTML5

You can use the pattern attribute. The required attribute is also needed, otherwise an input field with an empty value will be excluded from constraint validation.

<input pattern=".{3,}" required title="3 characters minimum">

<input pattern=".{5,10}" required title="5 to 10 characters">

Live Demo

http://jsfiddle.net/xhqsB/102/