Validation using Regular expression

Single Email :

 <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ErrorMessage="Please Enter Valid Email Address"
                                        ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*" ForeColor="Red"
                                        Display="Dynamic" ControlToValidate="txtEmail" SetFocusOnError="True">Please enter valid email address!</asp:RegularExpressionValidator>


Mutliple Email Id seprate with comma

<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"

                                ControlToValidate="txtEmail" Display="Dynamic" ErrorMessage="Enter valid email id"

                                SetFocusOnError="True" ValidationExpression="^(\s*,?\s*[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})+\s*$">*</asp:RegularExpressionValidator>


PDF : 



<asp:FileUpload ID="FileUpload2" runat="server" />
<asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server" ControlToValidate="FileUpload2" Display="Dynamic" ErrorMessage="Please Select  PDF."
                                            ValidationExpression=".*\.(pdf|PDF)">*</asp:RegularExpressionValidator> 


Image : 



 <asp:FileUpload ID="FileUpload1" runat="server" />
 <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="FileUpload1" Display="Dynamic" ErrorMessage="Please Enter a JPEG or GIF Image." ValidationExpression=".*\.(jpg|jpeg|gif|JPG|JPEG|GIF)">*</asp:RegularExpressionValidator> 


URL :



<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="Server" ControlToValidate="txtURL"  ValidationExpression="^(ht|f)tp(s?)\:\/\/[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*(:(0-9)*)*(\/?)([a-zA-Z0-9\-\.\?\,\'\/\\\+&amp;%\$#_]*)?$" ErrorMessage="Please enter a valid URL"
            Display="Dynamic" />

<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="Server" ControlToValidate="txtURL"
            ValidationExpression="(http|https)://([\w-]+\.)+[\w-]+(/[\w- ./?%&=]*)?" ErrorMessage="Please enter a valid URL"
            Display="Dynamic" />


Validate Number and greater than zero :


 <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="Server" ControlToValidate="TextBox1"
            ValidationExpression="^\d+$"
            ErrorMessage="Enter only numeric number and greater than zero" Display="Dynamic" />

4 digit code :
 

 <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="Server" ControlToValidate="TextBox1"
            ValidationExpression="^\d{4}$"
            ErrorMessage="Enter only 4 digit code" Display="Dynamic" />