Question

What is a good general regex (in PHP terms) to determine if a string is a valid XML tag name?

I startet using /[^>]+/i but that also matches something like 4 \<< which obviously isn’t a valid tag name.

So I tried combining all valid characters like /[a-z][a-z0-9_-]*/i which also isn’t quite right, as XML allows virtually any character in tag names also of foreign languages.

I’m stuck on that now – should I just check if there are whitespace characters? Or is there more to it?

Answer 1

why dont you just use an XML parser/generator which already knows the rules?

function isValidXmlElementName($elementName)
{
    try {
        new DOMElement($elementName);
    } catch (DOMException $e) {
        return false;
    }
    return true;
}

var_dump(isValidXmlElementName(' ')); // false 
var_dump(isValidXmlElementName('1')); // false
var_dump(isValidXmlElementName('-')); // false
var_dump(isValidXmlElementName('a')); // true