Question

I need a regular expression that can be used to find the N^th entry in a comma-separated list.

For example, say this list looks like this:

abc,def,4322,[e-mail],3321,alpha-beta,43

…and I wanted to find the value of the 7^th entry (alpha-beta).

Answer 1

My first thought would not be to use a regular expression, but to use something that splits the string into an array on the comma, but since you asked for a regex.

most regexes allow you to specify a minimum or maximum match, so something like this would probably work.

/(?:[^\,]*,){5}([^,]*)/

This is intended to match any number of character that are not a comma followed by a comma six times exactly (?:[^,]*,){5} – the ?: says to not capture – and then to match and capture any number of characters that are not a comma ([^,]+). You want to use the first capture group.

Let me know if you need more info.

EDIT: I edited the above to not capture the first part of the string. This regex works in C# and Ruby.