My sample code (the solution is actually the regex /^[a-zA-Z0-9]{6,20}$/) removes trailing line seperators (however they may currently be defined). A blank line will comprise two consecutive line seperators and will result in an invalid string being detected - which is consistent with OP's criteria (and original code).

Note that at least part of the rationale for posting a "complete sample" is to show others with a technique for providing stand alone code to demonstrate a problem or solution. The line handling code is incedental to the OP's question, but is an important part of a technique for providing test data.

Hmm, ok I'll go get that coffee now :)

DWIM is Perl's answer to Gödel

In reply to Re^3: how should i test whether a string contains between 6 and 20 letters and numbers by GrandFather
in thread how should i test whether a string contains between 6 and 20 letters and numbers by keiusui

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