An exploration of some of the issues facing Perl programmers
on EBCDIC based computers. We do not cover localization,
-internationalization, or multi byte character set issues other
+internationalization, or multi-byte character set issues other
than some discussion of UTF-8 and UTF-EBCDIC.
Portions that are still incomplete are marked with XXX.
integers running from 0 to 127 (decimal) that imply character
interpretation by the display and other systems of computers.
The range 0..127 can be covered by setting the bits in a 7-bit binary
-digit, hence the set is sometimes referred to as a "7-bit ASCII".
+digit, hence the set is sometimes referred to as "7-bit ASCII".
ASCII was described by the American National Standards Institute
document ANSI X3.4-1986. It was also described by ISO 646:1991
(with localization for currency symbols). The full ASCII set is
=head2 EBCDIC
The Extended Binary Coded Decimal Interchange Code refers to a
-large collection of single and multi byte coded character sets that are
+large collection of single- and multi-byte coded character sets that are
different from ASCII or ISO 8859-1 and are all slightly different from each
other; they typically run on host computers. The EBCDIC encodings derive from
-8 bit byte extensions of Hollerith punched card encodings. The layout on the
+8-bit byte extensions of Hollerith punched card encodings. The layout on the
cards was such that high bits were set for the upper and lower case alphabet
characters [a-z] and [A-Z], but there were gaps within each Latin alphabet
range.
in some other cases. The "names" of the controls listed here are
the Unicode Version 1 names, except for the few that don't have names, in which
case the names in the Wikipedia article were used
-(L<http://en.wikipedia.org/wiki/C0_and_C1_control_codes>.
+(L<http://en.wikipedia.org/wiki/C0_and_C1_control_codes>).
The differences between the 0037 and 1047 sets are
flagged with ***. The differences between the 1047 and POSIX-BC sets
are flagged with ###. All ord() numbers listed are decimal. If you
Obviously the first of these will fail to distinguish most ASCII platforms
from either a CCSID 0037, a 1047, or a POSIX-BC EBCDIC platform since "\r" eq
chr(13) under all of those coded character sets. But note too that
-because "\n" is chr(13) and "\r" is chr(10) on the MacIntosh (which is an
+because "\n" is chr(13) and "\r" is chr(10) on the Macintosh (which is an
ASCII platform) the second C<$is_ascii> test will lead to trouble there.
To determine whether or not perl was built under an EBCDIC
another a simple list of numbers, such as in the right columns in the
above table, along with perl's tr/// operator is all that is needed.
The data in the table are in ASCII/Latin1 order, hence the EBCDIC columns
-provide easy to use ASCII/Latin1 to EBCDIC operations that are also easily
+provide easy-to-use ASCII/Latin1 to EBCDIC operations that are also easily
reversed.
For example, to convert ASCII/Latin1 to code page 037 take the output of the
# OS/390 or z/OS example
$ebcdic_data = `echo '$ascii_data'| iconv -f ISO8859-1 -t IBM-1047`
-For other perl based conversion options see the Convert::* modules on CPAN.
+For other perl-based conversion options see the Convert::* modules on CPAN.
=head2 C RTL
-The OS/390 and z/OS C run time libraries provide _atoe() and _etoa() functions.
+The OS/390 and z/OS C run-time libraries provide _atoe() and _etoa() functions.
=head1 OPERATOR DIFFERENCES
=head1 REGULAR EXPRESSION DIFFERENCES
-As of perl 5.005_03 the letter range regular expression such as
+As of perl 5.005_03 the letter range regular expressions 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
=head1 SORTING
-One big difference between ASCII based character sets and EBCDIC ones
+One big difference between ASCII-based character sets and EBCDIC ones
are the relative positions of upper and lower case letters and the
-letters compared to the digits. If sorted on an ASCII based platform the
-two letter abbreviation for a physician comes before the two letter
-for drive, that is:
+letters compared to the digits. If sorted on an ASCII-based platform the
+two-letter abbreviation for a physician comes before the two letter
+abbreviation for drive; that is:
@sorted = sort(qw(Dr. dr.)); # @sorted holds ('Dr.','dr.') on ASCII,
# but ('dr.','Dr.') on EBCDIC
-The property of lower case before uppercase letters in EBCDIC is
+The property of lowercase before uppercase letters in EBCDIC is
even carried to the Latin 1 EBCDIC pages such as 0037 and 1047.
An example would be that E<Euml> C<E WITH DIAERESIS> (203) comes
before E<euml> C<e WITH DIAERESIS> (235) on an ASCII platform, but
the latter (83) comes before the former (115) on an EBCDIC platform.
-(Astute readers will note that the upper case version of E<szlig>
+(Astute readers will note that the uppercase version of E<szlig>
C<SMALL LETTER SHARP S> is simply "SS" and that the upper case version of
E<yuml> C<y WITH DIAERESIS> is not in the 0..255 range but it is
at U+x0178 in Unicode, or C<"\x{178}"> in a Unicode enabled Perl).
=head2 MONO CASE then sort data.
-In order to minimize the expense of mono casing mixed test try to
+In order to minimize the expense of mono casing mixed-case text, try to
C<tr///> towards the character set case most employed within the data.
If the data are primarily UPPERCASE non Latin 1 then apply tr/[a-z]/[A-Z]/
then sort(). If the data are primarily lowercase non Latin 1 then
address the E<yuml> C<y WITH DIAERESIS> character that will remain at
code point 255 on ASCII platforms, but 223 on most EBCDIC platforms
where it will sort to a place less than the EBCDIC numerals. With a
-Unicode enabled Perl you might try:
+Unicode-enabled Perl you might try:
tr/^?/\x{178}/;
=head2 Quoted-Printable encoding and decoding
-On ASCII encoded platforms it is possible to strip characters outside of
+On ASCII-encoded platforms it is possible to strip characters outside of
the printable set using:
# This QP encoder works on ASCII only
Caesar in his B<Gallic Wars> text. A single alphabet shift is sometimes
referred to as a rotation and the shift amount is given as a number $n after
the string 'rot' or "rot$n". Rot0 and rot26 would designate identity maps
-on the 26 letter English version of the Latin alphabet. Rot13 has the
+on the 26-letter English version of the Latin alphabet. Rot13 has the
interesting property that alternate subsequent invocations are identity maps
(thus rot13 is its own non-trivial inverse in the group of 26 alphabet
rotations). Hence the following is a rot13 encoder and decoder that will
To the extent that it is possible to write code that depends on
hashing order there may be differences between hashes as stored
-on an ASCII based platform and hashes stored on an EBCDIC based platform.
+on an ASCII-based platform and hashes stored on an EBCDIC-based platform.
XXX
=head1 I18N AND L10N
-Internationalization(I18N) and localization(L10N) are supported at least
-in principle even on EBCDIC platforms. The details are system dependent
+Internationalization (I18N) and localization (L10N) are supported at least
+in principle even on EBCDIC platforms. The details are system-dependent
and discussed under the L<perlebcdic/OS ISSUES> section below.
-=head1 MULTI OCTET CHARACTER SETS
+=head1 MULTI-OCTET CHARACTER SETS
Perl may work with an internal UTF-EBCDIC encoding form for wide characters
on EBCDIC platforms in a manner analogous to the way that it works with
=head1 OS ISSUES
-There may be a few system dependent issues
+There may be a few system-dependent issues
of concern to EBCDIC Perl programmers.
=head2 OS/400
=item PASE
-The PASE environment is runtime environment for OS/400 that can run
-executables built for PowerPC AIX in OS/400
, see L<perlos400>. PASE
+The PASE environment is a runtime environment for OS/400 that can run
+executables built for PowerPC AIX in OS/400
; see L<perlos400>. PASE
is ASCII-based, not EBCDIC-based as the ILE.
=item IFS access
projects / platform / upstream / perl.git / commitdiff