Question

I’d like to get some help regarding PHP.
Let’s say I have a string ($fullname).
I want to validate that it’s in the form of “Firstname_Lastname”.
For example, make sure that it’s “Nathan_Phillips” and not “Nathan Phillips” or “Nathan122” etc.
Can you guys help me with the function?

Thanks in advance! 🙂

———— EDIT ————-
Thank you guys! Managed to do that. Also added the numbers filter. Here’s the function:

function isValidName($name)
{
    if (strcspn($name, '0123456789') != strlen($name))
        return FALSE;
    $name = str_replace(" ", "", $name);
    $result = explode("_", $name);
    if(count($result) == 2)
        return TRUE;
    else
        return FALSE;
}

Usage example:

if(isValidName("Test_Test") == TRUE)
    echo "Valid name.";
else
    echo "Invalid name.";

Thanks again!

Answer 1

Maybe try something like this:

function checkInput($input) {
    $pattern = '/^[A-Za-z]{2,50}_[A-Za-z]{2,50}/';
    return preg_match($pattern, substr($input,3), $matches, PREG_OFFSET_CAPTURE);
}

This will accept a string containing 2-50 alphabetic characters, followed by an underscore, followed by 2-50 alphabetic characters.

I’m not the best with regex, so I invite corrections if anyone sees a flaw.

If you have special characters (è, í, etc.), the regex I gave probably won’t accept it. Also, it won’t accept names like O’Reilly or hyphenated names. See this:

Regex for names

I’ll let you track down all the exceptions to the regex for names, but I definitely think regex is the way to go.