You said "Exactly." and then went on to describe something completely different!

A regex is not required, nor is substr. The condition can be written as simply as: 

length == 9 and ! index $_, 5

[download]

Here's an example:

$ perl -E '
    my @strings = qw{1 234 5 678 567890123 qwerty};
    say for grep +(length == 9 and ! index $_, 5), @strings;
'
567890123

[download]

The 9 and 5 could be replaced with variables for greater flexibility; however, that wasn't what the OP asked for.

— Ken

In reply to Re^3: Need a regular expression to check the first digit by kcott
in thread Need a regular expression to check the first digit by chandantul

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