Question

I have 2 regexps in ruby. The first regex is for letters and digits something like:

letter_digits = /^([0-9]*[a-zA-Z][a-zA-Z0-9]*)$/

With this regex if I write only digits 564521 does not match!

However I have this regex for only digits:

only_digits = /^([0-9])*$/

But with this regex if I write s45xo does not match!

I need only 1 regex valid for both letters/digits and digits.

Answer 1

Try: letter_digits = /^[0-9a-zA-Z]*$/

Your first regexp /^([0-9]*[a-zA-Z][a-zA-Z0-9]*)$/ says that there should be digits (0 or more), then letter (1), then digits or letters (0 or more).

My advise is to read something about regexp, for example tutorial