Regular Expression: Allow letters, numbers, and spaces (with at least one letter or number)

Question

I\'m currently using this regex ^[A-Z0-9 _]*$ to accept letters, numbers, spaces and underscores. I need to modify it to require at least one number or letter s

Answer 1

^[ _]*[A-Z0-9][A-Z0-9 _]*$

You can optionally have some spaces or underscores up front, then you need one letter or number, and then an arbitrary number of numbers, letters, spaces or underscores after that.

Something that contains only spaces and underscores will fail the [A-Z0-9] portion.