perlebcdic.pod

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.

machines and cannot be generated as a C<"\c.letter."> control character on 
0037 machines.  Note also that "\c\\" maps to two characters
not one.

    chr   ord  8859-1               0037                1047 && POSIX-BC     
    ------------------------------------------------------------------------
    "\c?" 127  <DELETE>             "                   "              ***><
    "\c@"   0  <NULL>               <NULL>              <NULL>         ***><
    "\cA"   1  <S.O. HEADING>       <S.O. HEADING>      <S.O. HEADING> 
    "\cB"   2  <S.O. TEXT>          <S.O. TEXT>         <S.O. TEXT>
    "\cC"   3  <E.O. TEXT>          <E.O. TEXT>         <E.O. TEXT>
    "\cD"   4  <E.O. TRANS.>        <C1 28>             <C1 28> 
    "\cE"   5  <ENQUIRY>            <HORIZ. TAB.>       <HORIZ. TAB.>    
    "\cF"   6  <ACKNOWLEDGE>        <C1 6>              <C1 6>   
    "\cG"   7  <BELL>               <DELETE>            <DELETE>   
    "\cH"   8  <BACKSPACE>          <C1 23>             <C1 23>
    "\cI"   9  <HORIZ. TAB.>        <C1 13>             <C1 13>
    "\cJ"  10  <LINE FEED>          <C1 14>             <C1 14>
    "\cK"  11  <VERT. TAB.>         <VERT. TAB.>        <VERT. TAB.>
    "\cL"  12  <FORM FEED>          <FORM FEED>         <FORM FEED>    
    "\cM"  13  <CARRIAGE RETURN>    <CARRIAGE RETURN>   <CARRIAGE RETURN> 
    "\cN"  14  <SHIFT OUT>          <SHIFT OUT>         <SHIFT OUT>
    "\cO"  15  <SHIFT IN>           <SHIFT IN>          <SHIFT IN>
    "\cP"  16  <DATA LINK ESCAPE>   <DATA LINK ESCAPE>  <DATA LINK ESCAPE> 
    "\cQ"  17  <D.C. ONE>           <D.C. ONE>          <D.C. ONE>
    "\cR"  18  <D.C. TWO>           <D.C. TWO>          <D.C. TWO>
    "\cS"  19  <D.C. THREE>         <D.C. THREE>        <D.C. THREE> 
    "\cT"  20  <D.C. FOUR>          <C1 29>             <C1 29> 
    "\cU"  21  <NEG. ACK.>          <C1 5>              <LINE FEED>    ***
    "\cV"  22  <SYNCHRONOUS IDLE>   <BACKSPACE>         <BACKSPACE>
    "\cW"  23  <E.O. TRANS. BLOCK>  <C1 7>              <C1 7>
    "\cX"  24  <CANCEL>             <CANCEL>            <CANCEL>
    "\cY"  25  <E.O. MEDIUM>        <E.O. MEDIUM>       <E.O. MEDIUM>
    "\cZ"  26  <SUBSTITUTE>         <C1 18>             <C1 18>
    "\c["  27  <ESCAPE>             <C1 15>             <C1 15>
    "\c\\" 28  <FILE SEP.>\         <FILE SEP.>\        <FILE SEP.>\
    "\c]"  29  <GROUP SEP.>         <GROUP SEP.>        <GROUP SEP.>
    "\c^"  30  <RECORD SEP.>        <RECORD SEP.>       <RECORD SEP.>  ***><
    "\c_"  31  <UNIT SEP.>          <UNIT SEP.>         <UNIT SEP.>    ***><


=head1 FUNCTION DIFFERENCES

=over 8

=item chr()

chr() must be given an EBCDIC code number argument to yield a desired 
character return value on an EBCDIC machine.  For example:

    $CAPITAL_LETTER_A = chr(193);

=item ord()

ord() will return EBCDIC code number values on an EBCDIC machine.
For example:

    $the_number_193 = ord("A");

=item pack()

The c and C templates for pack() are dependent upon character set 
encoding.  Examples of usage on EBCDIC include:

    $foo = pack("CCCC",193,194,195,196);
    # $foo eq "ABCD"
    $foo = pack("C4",193,194,195,196);
    # same thing

    $foo = pack("ccxxcc",193,194,195,196);
    # $foo eq "AB\0\0CD"

=item print()

One must be careful with scalars and strings that are passed to
print that contain ASCII encodings.  One common place
for this to occur is in the output of the MIME type header for
CGI script writing.  For example, many perl programming guides 
recommend something similar to:

    print "Content-type:\ttext/html\015\012\015\012"; 
    # this may be wrong on EBCDIC

Under the IBM OS/390 USS Web Server or WebSphere on z/OS for example 
you should instead write that as:

    print "Content-type:\ttext/html\r\n\r\n"; # OK for DGW et alia

That is because the translation from EBCDIC to ASCII is done
by the web server in this case (such code will not be appropriate for
the Macintosh however).  Consult your web server's documentation for 
further details.

=item printf()

The formats that can convert characters to numbers and vice versa
will be different from their ASCII counterparts when executed
on an EBCDIC machine.  Examples include:

    printf("%c%c%c",193,194,195);  # prints ABC

=item sort()

EBCDIC sort results may differ from ASCII sort results especially for 
mixed case strings.  This is discussed in more detail below.

=item sprintf()

See the discussion of printf() above.  An example of the use
of sprintf would be:

    $CAPITAL_LETTER_A = sprintf("%c",193);

=item unpack()

See the discussion of pack() above.

=back

=head1 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 E<ocirc> C<o WITH CIRCUMFLEX> 
that lie between I and J would not be matched by the 
regular expression range C</[H-K]/>.  This works in
the other direction, too, if either of the range end points is
explicitly numeric: C<[\x89-\x91]> will match C<\x8e>, even
though C<\x89> is C<i> and C<\x91 > is C<j>, and C<\x8e>
is a gap character from the alphabetic viewpoint.

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 C</\313/> on EBCDIC or C</\364/> on ASCII machines to 
have your regular expression match C<o WITH CIRCUMFLEX>.

Another construct to be wary of is the inappropriate use of hex or
octal constants in regular expressions.  Consider the following
set of subs:

    sub is_c0 {
        my $char = substr(shift,0,1);
        $char =~ /[\000-\037]/;
    }

    sub is_print_ascii {
        my $char = substr(shift,0,1);
        $char =~ /[\040-\176]/;
    }

    sub is_delete {
        my $char = substr(shift,0,1);
        $char eq "\177";
    }

    sub is_c1 {
        my $char = substr(shift,0,1);
        $char =~ /[\200-\237]/;
    }

    sub is_latin_1 {
        my $char = substr(shift,0,1);
        $char =~ /[\240-\377]/;
    }

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 EBCDIC machine it may be desirable for constructs such as 
C<if (is_print_ascii("A")) {print "A is a printable character\n";}> 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:

    sub Is_c0 {
        my $char = substr(shift,0,1);
        if (ord('^')==94)  { # ascii
            return $char =~ /[\000-\037]/;
        } 
        if (ord('^')==176) { # 37
            return $char =~ /[\000-\003\067\055-\057\026\005\045\013-\023\074\075\062\046\030\031\077\047\034-\037]/;
        }
        if (ord('^')==95 || ord('^')==106) { # 1047 || posix-bc
            return $char =~ /[\000-\003\067\055-\057\026\005\025\013-\023\074\075\062\046\030\031\077\047\034-\037]/;
        }
    }

    sub Is_print_ascii {
        my $char = substr(shift,0,1);
        $char =~ /[ !"\#\$%&'()*+,\-.\/0-9:;<=>?\@A-Z[\\\]^_`a-z{|}~]/;
    }

    sub Is_delete {
        my $char = substr(shift,0,1);
        if (ord('^')==94)  { # ascii
            return $char eq "\177";
        }
        else  {              # ebcdic
            return $char eq "\007";
        }
    }

    sub Is_c1 {
        my $char = substr(shift,0,1);
        if (ord('^')==94)  { # ascii
            return $char =~ /[\200-\237]/;
        }
        if (ord('^')==176) { # 37
            return $char =~ /[\040-\044\025\006\027\050-\054\011\012\033\060\061\032\063-\066\010\070-\073\040\024\076\377]/;
        }
        if (ord('^')==95)  { # 1047
            return $char =~ /[\040-\045\006\027\050-\054\011\012\033\060\061\032\063-\066\010\070-\073\040\024\076\377]/;
        }
        if (ord('^')==106) { # posix-bc
            return $char =~ 
              /[\040-\045\006\027\050-\054\011\012\033\060\061\032\063-\066\010\070-\073\040\024\076\137]/;
        }
    }

    sub Is_latin_1 {
        my $char = substr(shift,0,1);
        if (ord('^')==94)  { # ascii
            return $char =~ /[\240-\377]/;
        }
        if (ord('^')==176) { # 37
            return $char =~ 
              /[\101\252\112\261\237\262\152\265\275\264\232\212\137\312\257\274\220\217\352\372\276\240\266\263\235\332\233\213\267\270\271\253\144\145\142\146\143\147\236\150\164\161-\163\170\165-\167\254\151\355\356\353\357\354\277\200\375\376\373\374\255\256\131\104\105\102\106\103\107\234\110\124\121-\123\130\125-\127\214\111\315\316\313\317\314\341\160\335\336\333\334\215\216\337]/;
        }
        if (ord('^')==95)  { # 1047
            return $char =~
              /[\101\252\112\261\237\262\152\265\273\264\232\212\260\312\257\274\220\217\352\372\276\240\266\263\235\332\233\213\267\270\271\253\144\145\142\146\143\147\236\150\164\161-\163\170\165-\167\254\151\355\356\353\357\354\277\200\375\376\373\374\272\256\131\104\105\102\106\103\107\234\110\124\121-\123\130\125-\127\214\111\315\316\313\317\314\341\160\335\336\333\334\215\216\337]/; 
        }
        if (ord('^')==106) { # posix-bc
            return $char =~ 
              /[\101\252\260\261\237\262\320\265\171\264\232\212\272\312\257\241\220\217\352\372\276\240\266\263\235\332\233\213\267\270\271\253\144\145\142\146\143\147\236\150\164\161-\163\170\165-\167\254\151\355\356\353\357\354\277\200\340\376\335\374\255\256\131\104\105\102\106\103\107\234\110\124\121-\123\130\125-\127\214\111\315\316\313\317\314\341\160\300\336\333\334\215\216\337]/;
        }
    }

Note however that only the C<Is_ascii_print()> sub is really independent 
of coded character set.  Another way to write C<Is_latin_1()> would be 
to use the characters in the range explicitly:

    sub Is_latin_1 {
        my $char = substr(shift,0,1);
        $char =~ /[牎ⅲぅΗī