Unique regular expression to check if a string contains letters and numbers

[ghighuphu]

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Darin.K wrote:

2.  Using my regex helper means I do not even have to worry about it or remembering the exact syntax of any of the posix classes.

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What is your regex helper, please?

[jcarmody]

https://decibel.ni.com/content/docs/DOC-13698

[jcarmody]

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@Darin.K wrote:

Missed the requirements:

single regex:

^([[:alpha:]]+[[:digit:]]+|[[:digit:]]+[[:alpha:]])[[:alnum:]]*$

You either have 1 or more digits followed by 1 or more letters or 1 or more letters followed by 1 or more digits. Once that is out of the way, the rest of the string must be all alphanumerics.  The ^ and $ make sure the whole string is included in the match.

(I have not tested this at all, just typed it up hopefully I got all the brackets in the right place).

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When I copied your regex and pasted it into a string constant, I got ^([[:alpha:]]+[[:digit:]]+|[[:digit:]]+[[:alpha:]]​?)[[:alnum:]]*$, but the question mark disappears when I paste it into this response.  Weird. 

Anyway, the question mark needs to be a "+" and it'll work.