Find special characters in string (using mask)

Hi all,

I have the following requirement, perhaps someone has got a hint for me:

I have got a string of 255 characters.

I want to realize that this string only contains characters of a "normal" format, like

a-z, A-Z and numbers.

Any characters like , - # for example are not allowed and I would like to know, how to check my string.

How can I achive that? With FIND or SEARCH?

I am not really familiar with these ABAP KEY WORDS. Can I use masks for example like

DATA: no_good type c value '[#,+,*...)

FIND no_good in STRING

or something like that?

Thanks and best regards

Andreas