sequence of characters that give the order and type of values, as
follows:
+ a A string with arbitrary binary data, will be null padded.
A An ascii string, will be space padded.
- a An ascii string, will be null padded.
+ Z A null terminated (asciz) string, will be null padded.
+
b A bit string (ascending bit order, like vec()).
B A bit string (descending bit order).
h A hex string (low nybble first).
X Back up a byte.
@ Null fill to absolute position.
+The following rules apply:
+
+=over 8
+
+=item *
+
Each letter may optionally be followed by a number giving a repeat
-count. With all types except C<"a">, C<"A">, C<"b">, C<"B">, C<"h">, C<"H">, and C<"P"> the
-pack function will gobble up that many values from the LIST. A C<*> for the
-repeat count means to use however many items are left. The C<"a"> and C<"A">
-types gobble just one value, but pack it as a string of length count,
-padding with nulls or spaces as necessary. (When unpacking, C<"A"> strips
-trailing spaces and nulls, but C<"a"> does not.) Likewise, the C<"b"> and C<"B">
-fields pack a string that many bits long. The C<"h"> and C<"H"> fields pack a
-string that many nybbles long. The C<"p"> type packs a pointer to a null-
-terminated string. You are responsible for ensuring the string is not a
-temporary value (which can potentially get deallocated before you get
-around to using the packed result). The C<"P"> packs a pointer to a structure
-of the size indicated by the length. A NULL pointer is created if the
-corresponding value for C<"p"> or C<"P"> is C<undef>.
-Real numbers (floats and doubles) are
-in the native machine format only; due to the multiplicity of floating
-formats around, and the lack of a standard "network" representation, no
-facility for interchange has been made. This means that packed floating
-point data written on one machine may not be readable on another - even if
-both use IEEE floating point arithmetic (as the endian-ness of the memory
-representation is not part of the IEEE spec). Note that Perl uses doubles
-internally for all numeric calculation, and converting from double into
-float and thence back to double again will lose precision (i.e.,
-C<unpack("f", pack("f", $foo)>) will not in general equal C<$foo>).
+count. With all types except C<"a">, C<"A">, C<"Z">, C<"b">, C<"B">, C<"h">,
+C<"H">, and C<"P"> the pack function will gobble up that many values from
+the LIST. A C<*> for the repeat count means to use however many items are
+left.
+
+=item *
+
+The C<"a">, C<"A"> and C<"Z"> types gobble just one value, but pack it as a
+string of length count, padding with nulls or spaces as necessary. When
+unpacking, C<"A"> strips trailing spaces and nulls, C<"Z"> strips everything
+after the first null, and C<"a"> returns data verbatim.
+
+=item *
+
+Likewise, the C<"b"> and C<"B"> fields pack a string that many bits long.
+
+=item *
+
+The C<"h"> and C<"H"> fields pack a string that many nybbles long.
+
+=item *
+
+The C<"p"> type packs a pointer to a null-terminated string. You are
+responsible for ensuring the string is not a temporary value (which can
+potentially get deallocated before you get around to using the packed result).
+The C<"P"> type packs a pointer to a structure of the size indicated by the
+length. A NULL pointer is created if the corresponding value for C<"p"> or
+C<"P"> is C<undef>.
+
+=item *
+
+Real numbers (floats and doubles) are in the native machine format only;
+due to the multiplicity of floating formats around, and the lack of a
+standard "network" representation, no facility for interchange has been
+made. This means that packed floating point data written on one machine
+may not be readable on another - even if both use IEEE floating point
+arithmetic (as the endian-ness of the memory representation is not part
+of the IEEE spec).
+
+Note that Perl uses doubles internally for all numeric calculation, and
+converting from double into float and thence back to double again will
+lose precision (i.e., C<unpack("f", pack("f", $foo)>) will not in general
+equal C<$foo>).
+
+=back
Examples:
$foo = pack("i9pl", gmtime);
# a real struct tm (on my system anyway)
+ $utmp_template = "Z8 Z8 Z16 L";
+ $utmp = pack($utmp_template, @utmp1);
+ # a struct utmp (BSDish)
+
+ @utmp2 = unpack($utmp_template, $utmp);
+ # "@utmp1" eq "@utmp2"
+
sub bintodec {
unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
}
-The same template may generally also be used in the unpack function.
+The same template may generally also be used in unpack().
=item package
$setbits = unpack("%32b*", $selectmask);
+See L</pack> for more examples.
+
=item untie VARIABLE
Breaks the binding between a variable and a package. (See C<tie()>.)
if (gimme != G_ARRAY) { /* arrange to do first one only */
/*SUPPRESS 530*/
for (patend = pat; !isALPHA(*patend) || *patend == 'x'; patend++) ;
- if (strchr("aAbBhHP", *patend) || *pat == '%') {
+ if (strchr("aAZbBhHP", *patend) || *pat == '%') {
patend++;
while (isDIGIT(*patend) || *patend == '*')
patend++;
s += len;
break;
case 'A':
+ case 'Z':
case 'a':
if (len > strend - s)
len = strend - s;
sv = NEWSV(35, len);
sv_setpvn(sv, s, len);
s += len;
- if (datumtype == 'A') {
+ if (datumtype == 'A' || datumtype == 'Z') {
aptr = s; /* borrow register */
- s = SvPVX(sv) + len - 1;
- while (s >= SvPVX(sv) && (!*s || isSPACE(*s)))
- s--;
- *++s = '\0';
+ if (datumtype == 'Z') { /* 'Z' strips stuff after first null */
+ s = SvPVX(sv);
+ while (*s)
+ s++;
+ }
+ else { /* 'A' strips both nulls and spaces */
+ s = SvPVX(sv) + len - 1;
+ while (s >= SvPVX(sv) && (!*s || isSPACE(*s)))
+ s--;
+ *++s = '\0';
+ }
SvCUR_set(sv, s - SvPVX(sv));
s = aptr; /* unborrow register */
}
sv_catpvn(cat, null10, len);
break;
case 'A':
+ case 'Z':
case 'a':
fromstr = NEXTFROM;
aptr = SvPV(fromstr, fromlen);
require Config; import Config;
}
-print "1..60\n";
+print "1..72\n";
$format = "c2 x5 C C x s d i l a6";
# Need the expression in here to force ary[5] to be numeric. This avoids
# binary values of the uuencoded version would not be portable between
# character sets. Uuencoding is meant for encoding binary data, not
# text data.
+
+# test the ascii template types (A, a, Z)
+
+print "not " unless pack('A*', "foo\0bar\0 ") eq "foo\0bar\0 ";
+print "ok ", $test++, "\n";
+
+print "not " unless pack('A11', "foo\0bar\0 ") eq "foo\0bar\0 ";
+print "ok ", $test++, "\n";
+
+print "not " unless unpack('A*', "foo\0bar \0") eq "foo\0bar";
+print "ok ", $test++, "\n";
+
+print "not " unless unpack('A8', "foo\0bar \0") eq "foo\0bar";
+print "ok ", $test++, "\n";
+
+print "not " unless pack('a*', "foo\0bar\0 ") eq "foo\0bar\0 ";
+print "ok ", $test++, "\n";
+
+print "not " unless pack('a11', "foo\0bar\0 ") eq "foo\0bar\0 \0\0";
+print "ok ", $test++, "\n";
+
+print "not " unless unpack('a*', "foo\0bar \0") eq "foo\0bar \0";
+print "ok ", $test++, "\n";
+
+print "not " unless unpack('a8', "foo\0bar \0") eq "foo\0bar ";
+print "ok ", $test++, "\n";
+
+print "not " unless pack('Z*', "foo\0bar\0 ") eq "foo\0bar\0 ";
+print "ok ", $test++, "\n";
+
+print "not " unless pack('Z11', "foo\0bar\0 ") eq "foo\0bar\0 \0\0";
+print "ok ", $test++, "\n";
+
+print "not " unless unpack('Z*', "foo\0bar \0") eq "foo";
+print "ok ", $test++, "\n";
+
+print "not " unless unpack('Z8', "foo\0bar \0") eq "foo";
+print "ok ", $test++, "\n";
+
projects / p5sagit/p5-mst-13.2.git / commitdiff