Validate Mobile Number With 10 Digits In ASP.NET

Using a Regular Expression, we can validate a TextBox with 10 digit mobile number in C#.

When asking a user to enter a mobile number, we usually validate if a number has 10 digits or not. If not, we ask user to enter full mobile number. In this case, I've a TextBox control on an ASP.NET Form. The following regular expression in ASPX file validates the number. 

.ASPX File

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox><br\>
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"
ControlToValidate="TextBox1" ErrorMessage="RegularExpressionValidator"
ValidationExpression="[0-9]{10}"></asp:RegularExpressionValidator>

Here are couple of detailed tutorials in regular expressions with code examples: 

• Top C# Regex Examples 
• List of Most Common Regular Expressions and Their Usage
• Regular Expressions in .NET