How to limit maximum and minimum number of text in asp.net textbox?

Question

I am trying to limit the number of text into a Textbox field. The requirement is to fix the minimum length as 7 and maximum length as 15.

I have tried to use the asp:RegularExpressionValidator to limit the number of text into the textbox.

Here is my code:

<asp:RegularExpressionValidator ID="revphone" runat="server" 
    Font-Size="16px"
    ValidationExpression="^[0-9]{7,15}$" 
    ControlToValidate="txtphonenumber" 
    ErrorMessage="*" 
    ValidationGroup="reg" 
    Display="Dynamic" 
    ForeColor="Red">
</asp:RegularExpressionValidator>Phone Number      
<asp:TextBox ID="txtphonenumber" runat="server" 
    placeholder="Phone Number" 
    Width="305px" 
    onblur="BtnRegisterClick()" 
    MaxLength="7">
</asp:TextBox>

I am able to get the minimum number but not getting the maximum number. It is limiting to type 7 digits only.

Answer 1

Here is Your Solution:-

 <asp:TextBox ID="txtphonenumber" runat="server"></asp:TextBox>
 <asp:RegularExpressionValidator Display = "Dynamic" ControlToValidate = "txtphonenumber" ID="revphone" ValidationExpression = "^[\s\S]{7,15}$" runat="server" ErrorMessage="Minimum 7 and Maximum 15 characters required."></asp:RegularExpressionValidator>

For More Info Refer this Below Link.....

https://www.aspsnippets.com/Articles/TextBox-Minimum-and-Maximum-Character-Length-Validation-using-ASPNet-RegularExpression-Validators.aspx