Create xml

index.php

<?php

function addXml($name, $input = null, $attrs = [])
{
    $xml = "";
    $xml .= "<{$name}";
    if (!empty($attrs)) {
        foreach($attrs as $key => $value) {
            $xml .= " {$key}=\"{$value}\"";
        }
	}
	if ($input == null) {
		$xml .= "/>";
	} else {
		$xml .= ">";
		$xml .= $input;
    	$xml .= "</{$name}>";
	}
    
    return $xml;
}

// normal node
addXml("name", null, ["id" => 1]); // <name id="1"/>

// closing node
addXml("name", "jan", ["id" => 1]); // <name id="1">jan</name>

// multiple nodes
addXml("Root", addXml("Child", 1), ["xmlns:xsi" => "http://www.w3.org/2001/XMLSchema-instance"]); // <Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Child>1</Child></Root>