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finding length of encrypted(binary) string

by linuxfan (Beadle)
on Dec 03, 2004 at 22:19 UTC ( #412300=perlquestion: print w/replies, xml ) Need Help??

linuxfan has asked for the wisdom of the Perl Monks concerning the following question:

Hi, My perl script reads an encrypted string from a server. It then calculates the length of this string and sends this number along with the string back to the server. I am using:
$str = read_str_from_server($args);
$len = length $str;

Based on the server response, I think that the above method fails for certain values of $str and $len. Is there an alternate function to count the nubmer of "bytes" in the encrypted string?


  • Comment on finding length of encrypted(binary) string

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Re: finding length of encrypted(binary) string
by bart (Canon) on Dec 03, 2004 at 22:49 UTC
    You can enforce the string to be treated as pure bytes, by pushing it through an incantation of pack. Then, length will work.
    my $bytes_string = pack 'C0a*', $string; my $bytecount = length $bytes_string;
Re: finding length of encrypted(binary) string
by BrowserUk (Patriarch) on Dec 03, 2004 at 22:29 UTC

    Sounds like your binary data is being mistaken for unicode data. Using the bytes pragma, optionally localised around the call to length should fix the problem.

    $s = "\x{200}\x{400}\x{301}"; print length $s; 3 print do{ use bytes; length $s }; 6

    Examine what is said, not who speaks.
    "But you should never overestimate the ingenuity of the sceptics to come up with a counter-argument." -Myles Allen
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      Thanks for your reply. I realized I was not using the

      use bytes pragma

      in a different place in the program while extracting the encrypted text, and this was causing my program to fail. My program works like a charm now!

Re: finding length of encrypted(binary) string
by Zed_Lopez (Chaplain) on Dec 03, 2004 at 22:23 UTC

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