Here, you have good advice: "I ... consider regex expressions as the wrong solution. They're notoriously hard to get right."

However, the conclusion of "use something somebody else wrote that does it properly", while valid, is asking a lot. As regex is hard to get right, don't assume the code you find on the web or book or via some other means works correctly.

My rule is if I didn't write it and can't wrap my head around the code to convince myself it is the right solution, I don't use it. And as I think others have written, there are some interactive online tests for regex expressions that can help.