In my program I have a account ID and I want to create a username. It is cannot contain numeric values at the start of their name unless those numeric numbers are equal to their account ID number. For example if I am seller ID 44 and I try to create username “37verifier” it is not fine. But if I try to create 44Verifier then it is fine. If I try to create “A37verifier”, again this is fine. And also allowed only "@ and .(dot)" special character in name (if it is email id format), not allowed other special characters in my username.
How can I do it in a php script? Please help me.