Basics Everybody knows the Quantifiers + and *. Most will also know ?. But do you know that they are only shortcuts for convenience? No? The real quantifier in regular expressions is {m,n} where m is a number that defines the minimum amount to match and n is the number that defines the upper bound. The upper […]

Why not? Imagine you have a regex to validate a password ^(?=.*\p{Lu})(?=.*\P{L})\S{8,}$  Thats not too complicated, but the readability could be better. The solution here is the option x or IgnorePatternWhitespace. Most regular expression flavours allow you to use the option x, this is an important option everybody should know, who want to write longer patterns. […]

Of course, the ultimate tool is RegexBuddy by Jan Goyvaerts. I personally don’t have it at the moment, but I surely need to get it soon. It supports various languages, gives you detailed explanation on each part, you can step through the matching process … But if you use regex not often and do only small ones, […]

No, I am not going into theoretical definitions. I am going to talk about regex in todays computer languages and applications. I am surprised how many programmers think regexes are complicated and ask e.g. on Stackoverflow for a regex for a specific task. They will get most probably an answer, if they ask nicely. But […]