How to write a regular expression for something that does NOT start with a given word
Let's suppose I have the following list
I want a regular expression that returns all but June and July because they they start with Ju
I wrote something like this ^[^ju] but this return any starting with J or U I need something that starts with Ju Thank you for your help
Try this regular expression:
^([^j].*|j($|[^u].*))
This matches strings that either do not start with j, or if they start with j there is not a u at the second position.
If you can use look-around assertions, you can also use this:
^(?!ju).*
Could you please tell us, which language you are using?
For example if you need the PCRE for Apache's mod_rewrite, you could simple prepend ! to the PCRE to negate it.
In PHP on the other hand you would use a negative lookahead assertion as Gumbo described.
It's a bad idea to use regular expressions for complement matches. It works, but it is usually either really inefficient or engine-specific. Use a regex and combine it with the not operator instead.