perlebcdic.1

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

.IX Header "REGULAR EXPRESSION DIFFERENCES"
As of perl 5.005_03 the letter range regular expression such as 
[A\-Z] and [a\-z] have been especially coded to not pick up gap 
characters.  For example, characters such as o\*^ \f(CW\*(C`o WITH CIRCUMFLEX\*(C'\fR 
that lie between I and J would not be matched by the 
regular expression range \f(CW\*(C`/[H\-K]/\*(C'\fR.  This works in
the other direction, too, if either of the range end points is
explicitly numeric: \f(CW\*(C`[\ex89\-\ex91]\*(C'\fR will match \f(CW\*(C`\ex8e\*(C'\fR, even
though \f(CW\*(C`\ex89\*(C'\fR is \f(CW\*(C`i\*(C'\fR and \f(CW\*(C`\ex91 \*(C'\fR is \f(CW\*(C`j\*(C'\fR, and \f(CW\*(C`\ex8e\*(C'\fR
is a gap character from the alphabetic viewpoint.
.PP
If you do want to match the alphabet gap characters in a single octet 
regular expression try matching the hex or octal code such 
as \f(CW\*(C`/\e313/\*(C'\fR on \s-1EBCDIC\s0 or \f(CW\*(C`/\e364/\*(C'\fR on \s-1ASCII\s0 machines to 
have your regular expression match \f(CW\*(C`o WITH CIRCUMFLEX\*(C'\fR.
.PP
Another construct to be wary of is the inappropriate use of hex or
octal constants in regular expressions.  Consider the following
set of subs:
.PP
.Vb 4
\&    sub is_c0 {
\&        my $char = substr(shift,0,1);
\&        $char =~ /[\e000\-\e037]/;
\&    }
\&
\&    sub is_print_ascii {
\&        my $char = substr(shift,0,1);
\&        $char =~ /[\e040\-\e176]/;
\&    }
\&
\&    sub is_delete {
\&        my $char = substr(shift,0,1);
\&        $char eq "\e177";
\&    }
\&
\&    sub is_c1 {
\&        my $char = substr(shift,0,1);
\&        $char =~ /[\e200\-\e237]/;
\&    }
\&
\&    sub is_latin_1 {
\&        my $char = substr(shift,0,1);
\&        $char =~ /[\e240\-\e377]/;
\&    }
.Ve
.PP
The above would be adequate if the concern was only with numeric code points.
However, the concern may be with characters rather than code points 
and on an \s-1EBCDIC\s0 machine it may be desirable for constructs such as 
\&\f(CW\*(C`if (is_print_ascii("A")) {print "A is a printable character\en";}\*(C'\fR to print
out the expected message.  One way to represent the above collection
of character classification subs that is capable of working across the
four coded character sets discussed in this document is as follows:
.PP
.Vb 12
\&    sub Is_c0 {
\&        my $char = substr(shift,0,1);
\&        if (ord(\*(Aq^\*(Aq)==94)  { # ascii
\&            return $char =~ /[\e000\-\e037]/;
\&        } 
\&        if (ord(\*(Aq^\*(Aq)==176) { # 37
\&            return $char =~ /[\e000\-\e003\e067\e055\-\e057\e026\e005\e045\e013\-\e023\e074\e075\e062\e046\e030\e031\e077\e047\e034\-\e037]/;
\&        }
\&        if (ord(\*(Aq^\*(Aq)==95 || ord(\*(Aq^\*(Aq)==106) { # 1047 || posix\-bc
\&            return $char =~ /[\e000\-\e003\e067\e055\-\e057\e026\e005\e025\e013\-\e023\e074\e075\e062\e046\e030\e031\e077\e047\e034\-\e037]/;
\&        }
\&    }
\&
\&    sub Is_print_ascii {
\&        my $char = substr(shift,0,1);
\&        $char =~ /[ !"\e#\e$%&\*(Aq()*+,\e\-.\e/0\-9:;<=>?\e@A\-Z[\e\e\e]^_\`a\-z{|}~]/;
\&    }
\&
\&    sub Is_delete {
\&        my $char = substr(shift,0,1);
\&        if (ord(\*(Aq^\*(Aq)==94)  { # ascii
\&            return $char eq "\e177";
\&        }
\&        else  {              # ebcdic
\&            return $char eq "\e007";
\&        }
\&    }
\&
\&    sub Is_c1 {
\&        my $char = substr(shift,0,1);
\&        if (ord(\*(Aq^\*(Aq)==94)  { # ascii
\&            return $char =~ /[\e200\-\e237]/;
\&        }
\&        if (ord(\*(Aq^\*(Aq)==176) { # 37
\&            return $char =~ /[\e040\-\e044\e025\e006\e027\e050\-\e054\e011\e012\e033\e060\e061\e032\e063\-\e066\e010\e070\-\e073\e040\e024\e076\e377]/;
\&        }
\&        if (ord(\*(Aq^\*(Aq)==95)  { # 1047
\&            return $char =~ /[\e040\-\e045\e006\e027\e050\-\e054\e011\e012\e033\e060\e061\e032\e063\-\e066\e010\e070\-\e073\e040\e024\e076\e377]/;
\&        }
\&        if (ord(\*(Aq^\*(Aq)==106) { # posix\-bc
\&            return $char =~ 
\&              /[\e040\-\e045\e006\e027\e050\-\e054\e011\e012\e033\e060\e061\e032\e063\-\e066\e010\e070\-\e073\e040\e024\e076\e137]/;
\&        }
\&    }
\&
\&    sub Is_latin_1 {
\&        my $char = substr(shift,0,1);
\&        if (ord(\*(Aq^\*(Aq)==94)  { # ascii
\&            return $char =~ /[\e240\-\e377]/;
\&        }
\&        if (ord(\*(Aq^\*(Aq)==176) { # 37
\&            return $char =~ 
\&              /[\e101\e252\e112\e261\e237\e262\e152\e265\e275\e264\e232\e212\e137\e312\e257\e274\e220\e217\e352\e372\e276\e240\e266\e263\e235\e332\e233\e213\e267\e270\e271\e253\e144\e145\e142\e146\e143\e147\e236\e150\e164\e161\-\e163\e170\e165\-\e167\e254\e151\e355\e356\e353\e357\e354\e277\e200\e375\e376\e373\e374\e255\e256\e131\e104\e105\e102\e106\e103\e107\e234\e110\e124\e121\-\e123\e130\e125\-\e127\e214\e111\e315\e316\e313\e317\e314\e341\e160\e335\e336\e333\e334\e215\e216\e337]/;
\&        }
\&        if (ord(\*(Aq^\*(Aq)==95)  { # 1047
\&            return $char =~
\&              /[\e101\e252\e112\e261\e237\e262\e152\e265\e273\e264\e232\e212\e260\e312\e257\e274\e220\e217\e352\e372\e276\e240\e266\e263\e235\e332\e233\e213\e267\e270\e271\e253\e144\e145\e142\e146\e143\e147\e236\e150\e164\e161\-\e163\e170\e165\-\e167\e254\e151\e355\e356\e353\e357\e354\e277\e200\e375\e376\e373\e374\e272\e256\e131\e104\e105\e102\e106\e103\e107\e234\e110\e124\e121\-\e123\e130\e125\-\e127\e214\e111\e315\e316\e313\e317\e314\e341\e160\e335\e336\e333\e334\e215\e216\e337]/; 
\&        }
\&        if (ord(\*(Aq^\*(Aq)==106) { # posix\-bc
\&            return $char =~ 
\&              /[\e101\e252\e260\e261\e237\e262\e320\e265\e171\e264\e232\e212\e272\e312\e257\e241\e220\e217\e352\e372\e276\e240\e266\e263\e235\e332\e233\e213\e267\e270\e271\e253\e144\e145\e142\e146\e143\e147\e236\e150\e164\e161\-\e163\e170\e165\-\e167\e254\e151\e355\e356\e353\e357\e354\e277\e200\e340\e376\e335\e374\e255\e256\e131\e104\e105\e102\e106\e103\e107\e234\e110\e124\e121\-\e123\e130\e125\-\e127\e214\e111\e315\e316\e313\e317\e314\e341\e160\e300\e336\e333\e334\e215\e216\e337]/;
\&        }
\&    }
.Ve
.PP
Note however that only the \f(CW\*(C`Is_ascii_print()\*(C'\fR sub is really independent 
of coded character set.  Another way to write \f(CW\*(C`Is_latin_1()\*(C'\fR would be 
to use the characters in the range explicitly:
.PP
.Vb 4
\&    sub Is_latin_1 {
\&        my $char = substr(shift,0,1);
\&        $char =~ /[\ XXXXXXXXXXXX\%XXXXXXXXXXXXXXXXXXA\*`A\*'A\*^A\*~A\*:A\*o\*(AEC\*,E\*`E\*'E\*^E\*:I\*`I\*'I\*^I\*:\*(D\-N\*~O\*`O\*'O\*^O\*~O\*:XO\*/U\*`U\*'U\*^U\*:Y\*'\*(Th\*8a\*`a\*'a\*^a\*~a\*:a\*o\*(aec\*,e\*`e\*'e\*^e\*:i\*`i\*'i\*^i\*:\*(d\-n\*~o\*`o\*'o\*^o\*~o\*:Xo\*/u\*`u\*'u\*^u\*:y\*'\*(thy\*:]/;
\&    }
.Ve
.PP
Although that form may run into trouble in network transit (due to the 
presence of 8 bit characters) or on non ISO-Latin character sets.
.SH "SOCKETS"
.IX Header "SOCKETS"
Most socket programming assumes \s-1ASCII\s0 character encodings in network
byte order.  Exceptions can include \s-1CGI\s0 script writing under a
host web server where the server may take care of translation for you.
Most host web servers convert \s-1EBCDIC\s0 data to \s-1ISO\-8859\-1\s0 or Unicode on
output.
.SH "SORTING"
.IX Header "SORTING"
One big difference between \s-1ASCII\s0 based character sets and \s-1EBCDIC\s0 ones
are the relative positions of upper and lower case letters and the
letters compared to the digits.  If sorted on an \s-1ASCII\s0 based machine the
two letter abbreviation for a physician comes before the two letter
for drive, that is:
.PP
.Vb 2
\&    @sorted = sort(qw(Dr. dr.));  # @sorted holds (\*(AqDr.\*(Aq,\*(Aqdr.\*(Aq) on ASCII,
\&                                  # but (\*(Aqdr.\*(Aq,\*(AqDr.\*(Aq) on EBCDIC
.Ve
.PP
The property of lower case before uppercase letters in \s-1EBCDIC\s0 is
even carried to the Latin 1 \s-1EBCDIC\s0 pages such as 0037 and 1047.
An example would be that E\*: \f(CW\*(C`E WITH DIAERESIS\*(C'\fR (203) comes 
before e\*: \f(CW\*(C`e WITH DIAERESIS\*(C'\fR (235) on an \s-1ASCII\s0 machine, but 
the latter (83) comes before the former (115) on an \s-1EBCDIC\s0 machine.  
(Astute readers will note that the upper case version of \*8 
\&\f(CW\*(C`SMALL LETTER SHARP S\*(C'\fR is simply \*(L"\s-1SS\s0\*(R" and that the upper case version of 
y\*: \f(CW\*(C`y WITH DIAERESIS\*(C'\fR is not in the 0..255 range but it is 
at U+x0178 in Unicode, or \f(CW"\ex{178}"\fR in a Unicode enabled Perl).
.PP
The sort order will cause differences between results obtained on
\&\s-1ASCII\s0 machines versus \s-1EBCDIC\s0 machines.  What follows are some suggestions
on how to deal with these differences.
.Sh "Ignore \s-1ASCII\s0 vs. \s-1EBCDIC\s0 sort differences."
.IX Subsection "Ignore ASCII vs. EBCDIC sort differences."
This is the least computationally expensive strategy.  It may require
some user education.
.Sh "\s-1MONO\s0 \s-1CASE\s0 then sort data."
.IX Subsection "MONO CASE then sort data."
In order to minimize the expense of mono casing mixed test try to
\&\f(CW\*(C`tr///\*(C'\fR towards the character set case most employed within the data.
If the data are primarily \s-1UPPERCASE\s0 non Latin 1 then apply tr/[a\-z]/[A\-Z]/
then \fIsort()\fR.  If the data are primarily lowercase non Latin 1 then
apply tr/[A\-Z]/[a\-z]/ before sorting.  If the data are primarily \s-1UPPERCASE\s0
and include Latin\-1 characters then apply:
.PP
.Vb 3
\&    tr/[a\-z]/[A\-Z]/; 
\&    tr/[a\*`a\*'a\*^a\*~a\*:a\*o\*(aec\*,e\*`e\*'e\*^e\*:i\*`i\*'i\*^i\*:\*(d\-n\*~o\*`o\*'o\*^o\*~o\*:o\*/u\*`u\*'u\*^u\*:y\*'\*(th]/[A\*`A\*'A\*^A\*~A\*:A\*o\*(AEC\*,E\*`E\*'E\*^E\*:I\*`I\*'I\*^I\*:\*(D\-N\*~O\*`O\*'O\*^O\*~O\*:O\*/U\*`U\*'U\*^U\*:Y\*'\*(Th]/;
\&    s/\*8/SS/g;
.Ve
.PP
then \fIsort()\fR.  Do note however that such Latin\-1 manipulation does not 
address the y\*: \f(CW\*(C`y WITH DIAERESIS\*(C'\fR character that will remain at 
code point 255 on \s-1ASCII\s0 machines, but 223 on most \s-1EBCDIC\s0 machines 
where it will sort to a place less than the \s-1EBCDIC\s0 numerals.  With a 
Unicode enabled Perl you might try:
.PP
.Vb 1
\&    tr/^?/\ex{178}/;
.Ve
.PP
The strategy of mono casing data before sorting does not preserve the case 
of the data and may not be acceptable for that reason.
.Sh "Convert, sort data, then re convert."
.IX Subsection "Convert, sort data, then re convert."
This is the most expensive proposition that does not employ a network
connection.
.Sh "Perform sorting on one type of machine only."
.IX Subsection "Perform sorting on one type of machine only."
This strategy can employ a network connection.  As such
it would be computationally expensive.
.SH "TRANSFORMATION FORMATS"
.IX Header "TRANSFORMATION FORMATS"
There are a variety of ways of transforming data with an intra character set 
mapping that serve a variety of purposes.  Sorting was discussed in the 
previous section and a few of the other more popular mapping techniques are 
discussed next.
.Sh "\s-1URL\s0 decoding and encoding"
.IX Subsection "URL decoding and encoding"
Note that some URLs have hexadecimal \s-1ASCII\s0 code points in them in an
attempt to overcome character or protocol limitation issues.  For example 
the tilde character is not on every keyboard hence a \s-1URL\s0 of the form:
.PP
.Vb 1
\&    http://www.pvhp.com/~pvhp/
.Ve
.PP
may also be expressed as either of:
.PP
.Vb 1
\&    http://www.pvhp.com/%7Epvhp/
\&
\&    http://www.pvhp.com/%7epvhp/
.Ve
.PP
where 7E is the hexadecimal \s-1ASCII\s0 code point for '~'.  Here is an example
of decoding such a \s-1URL\s0 under \s-1CCSID\s0 1047:
.PP
.Vb 10
\&    $url = \*(Aqhttp://www.pvhp.com/%7Epvhp/\*(Aq;
\&    # this array assumes code page 1047
\&    my @a2e_1047 = (
\&          0,  1,  2,  3, 55, 45, 46, 47, 22,  5, 21, 11, 12, 13, 14, 15,
\&         16, 17, 18, 19, 60, 61, 50, 38, 24, 25, 63, 39, 28, 29, 30, 31,
\&         64, 90,127,123, 91,108, 80,125, 77, 93, 92, 78,107, 96, 75, 97,
\&        240,241,242,243,244,245,246,247,248,249,122, 94, 76,126,110,111,
\&        124,193,194,195,196,197,198,199,200,201,209,210,211,212,213,214,
\&        215,216,217,226,227,228,229,230,231,232,233,173,224,189, 95,109,
\&        121,129,130,131,132,133,134,135,136,137,145,146,147,148,149,150,
\&        151,152,153,162,163,164,165,166,167,168,169,192, 79,208,161,  7,
\&         32, 33, 34, 35, 36, 37,  6, 23, 40, 41, 42, 43, 44,  9, 10, 27,
\&         48, 49, 2