Question

I would like to match the numbers 123456789 and 012 using only one regex in the following strings. I am not sure how to handle all the following scenarios with a single regex:

<one><num>123456789</num><code>012</code></one>

<two><code>012</code><num>123456789</num></two>

<three num="123456789" code="012" />

<four code="012" num="123456789" />

<five code="012"><num>123456789</num></five>

<six num="123456789"><code>012</code></six>

They also don’t have to be on the same line like above, for example:

<seven>
<num>123456789</num>
<code>012</code>
</seven>

Answer 1

Parsing XML with regex is not a good idea. You can use XPath or xlinq. xlinq is easier. You must reference System.Xml.Linq and System.Xml and add using declerations. I wrote the code on here, not in visual studio, so there may be minor bugs…

// var xml = ** load xml string
var document = XDocument.Parse(xml);

foreach(var i in document.Root.Elements())
{
    var num = ""; 
    var code = "";

    if(i.Attributes("num").Length > 0)
    {
        Console.WriteLine("Num: {0}", i.Attributes("num")[0].Value);
        Console.WriteLine("Code: {0}", i.Attributes("code")[0].Value);
    }
    else
    {
        Console.WriteLine("Num: {0}", i.Element("num").Value);
        Console.WriteLine("Code: {0}", i.Element("code").Value);
    }
}