On 07/16/2012 04:05 PM, De-Jian Zhao wrote:
Hi,
I want to change the record separator in a Perl one liner with ">" as the
separator. However, I tried without success.
The perlrun document
(http://perldoc.perl.org/perlrun.html#Command-Switches) says that*
"***-0*[/octal/hexadecimal/] * specifies the input record separator (|$/|
) as an octal or hexadecimal number. *"
*When I tried to get the octal/hexadecimal code of ">" with oct(">") and
hex(">"), I got "0". I used this number and it did not work the way I
wanted (perl -00 -ne 'print if /AAAA/' test.seq ).
From 'perldoc -f oct'
...
oct Interprets EXPR as an octal string and returns the corresponding
value.
...
To go the other way (produce a
number in octal), use sprintf() or printf():
$perms = (stat("filename"))[2] & 07777;
$oct_perms = sprintf "%lo", $perms;
So it is used for converting a string into an octal value. But we can go
the other way with printf and ord:
perl -e 'printf "%lo\n", ord(q{>})'
76
Now perl will leave the input record separator on the string, but we can
take that off with chop:
echo 'AAAA>BBBB>CCCC' | perl -0076 -nE 'chop,say if /AAAA/'
AAAA
TIMTOWTDI of course, and you could also do it like this:
echo 'AAAA>BBBB>CCCC' | perl -nE 'for (split />/) { say if /AAAA/ }'
AAAA
Cheers,
Michael
Do the functions (oct and hex) return the octal and hexadecimal value of
the inputted character? The document on the web seems to give different
answers.
http://perldoc.perl.org/index-functions-by-cat.html#Functions-for-SCALARs-or-strings
hex <http://perldoc.perl.org/functions/hex.html> - convert a string to a
hexadecimal number
oct <http://perldoc.perl.org/functions/oct.html> - convert a string to an
octal number
http://perldoc.perl.org/functions/hex.html
*hex EXPR **hex* Interprets EXPR as a hex string and returns the
corresponding value.
http://perldoc.perl.org/functions/oct.html
*oct EXPR **oct* Interprets EXPR as an octal string and returns the
corresponding value.
I tested the functions. The first description is possibly wrong. If I am
right, which functions could be used to get the octal and hexadecimal
number of a string? How should the Perl one liner be written to change
the record sepatator to ">"? Thanks for your attention.
Dejian
--
Michael Brader Senior Software Engineer and Perl Person
Technology/Softdev/M&E Small Change Team
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