regex to check the string contains only letter and numbers but not only numbers

Question

I need a help with regex which checks the string contains only letter and numbers but not only numbers

Valid

* letters
* 1wret
* 0123chars
* chars0123
*          


        

Answer 1

Here are the components of the regex we're going to use:

• ^ and $ are the beginning and end of the string anchors respectively
• \d matches a digit
• [a-zA-Z] matches a letter
• [a-zA-Z\d] matches a letter or a digit
• * is "zero-or-more" repetition

With these, we can now compose the regex we need (see on rubular.com):

^\d*[a-zA-Z][a-zA-Z\d]*$

Here's an explanation of the pattern:

from the beginning...  till the end
|                      |
^\d*[a-zA-Z][a-zA-Z\d]*$
 \_/\______/\_________/

The 3 parts are:

• Maybe some digits as a prefix...
• But then definitely a letter!
• And then maybe some digits and letters as a suffix

References

• regular-expressions.info/Character Class, Anchors, and Repetition