I have one problem. I am having two pages. In first page if I leave some mantitoy fields empty and if I click submit. The same first page must be displayed with changing the color(to red) of the names of the manditory fields that are not filled but all other data in other fields must be there. I don't know how to do it. Since I am new to php and using PHP3. Please help me.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions.
Consider email address RFCs:
Look at HTML5 form input element (with type=email) regex pattern: