It's a good idea to always check if a regex succeeds before using $1 and friends, or you may get a result from a previous match. One way to do this implicitly: ($newValue) = $oldValue =~ /_(\d+)\./; This leaves $newValue as undef on failure (because the match returns an empty list). You can even set newValue and check the result all at once: ($newValue) = $oldValue =~ /_(\d+)\./ or warn "bad format: '$oldValue'"; or 
if (($newValue) = $oldValue =~ /_(\d+)\./) {
   # all is ok
} else {
   # something went wrong
}

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In reply to Re: (2) Remove non-numerics from string by ysth
in thread Remove non-numerics from string by Anonymous Monk

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