You are using strings like "10.02.2000" as if they were numbers, so perl obligingly converts as much as it can to a number, "10.02.2000", becoming 10.02, and warns you that part of the string didn't look like part of the number.

You could do a string match instead:

if ($sw_fields[2] =~ /^$ver\./) # does it start with $ver and .?
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but its hard to check for major version >= 10 that way. Depending on what all you are doing, spliting up the version is probably better:

my ($major, $minor, $subminor) = split /\./, $sw_fields[2];
if ($major >= 10)
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