# Question for programmers [Regular Expressions 2]

As with all the programmer questions, I will update the post with the answer after people comment on this. Today's question is:

You have a list of regular expressions for strings to be matched against. You need to turn them into a single regular expression. How can you do it so that a string needs to match any of the initial regular expressions? How can you do it to match them all at the same time?

## Comments

For matching any pattern, just concatenate them with pipe symbols: (regex1)|(regex2)|(regex3) Matching all of them can be achieved using positive look-aheads: (?=.*regex1)(?=.*regex2)regex3 Note that the `.*` might become expensive. If the patterns attempt to match the entire string (are of the form `^...$`), then the `.*`s can be left out.

Cristian Lupașcu