diff options
Diffstat (limited to 'perl.man.3')
| -rw-r--r-- | perl.man.3 | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/perl.man.3 b/perl.man.3 index be1cc72e2b..d4574ebd69 100644 --- a/perl.man.3 +++ b/perl.man.3 @@ -1,7 +1,10 @@ ''' Beginning of part 3 -''' $Header: perl_man.3,v 3.0.1.11 90/11/10 01:48:21 lwall Locked $ +''' $Header: perl_man.3,v 3.0.1.12 91/01/11 18:18:15 lwall Locked $ ''' ''' $Log: perl.man.3,v $ +''' Revision 3.0.1.12 91/01/11 18:18:15 lwall +''' patch42: added binary and hex pack/unpack options +''' ''' Revision 3.0.1.11 90/11/10 01:48:21 lwall ''' patch38: random cleanup ''' patch38: documented tr///cds @@ -291,17 +294,24 @@ of values, as follows: X Back up a byte. @ Null fill to absolute position. u A uuencoded string. + b A bit string (ascending bit order, like vec()). + B A bit string (descending bit order). + h A hex string (low nybble first). + H A hex string (high nybble first). .fi Each letter may optionally be followed by a number which gives a repeat count. -With all types except "a" and "A" the pack function will gobble up that many values +With all types except "a", "A", "b", "B", "h" and "H", +the pack function will gobble up that many values from the LIST. A * for the repeat count means to use however many items are left. The "a" and "A" types gobble just one value, but pack it as a string of length count, padding with nulls or spaces as necessary. (When unpacking, "A" strips trailing spaces and nulls, but "a" does not.) +Likewise, the "b" and "B" fields pack a string that many bits long. +The "h" and "H" fields pack a string that many nybbles long. 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 \*(L"network\*(R" representation, no facility for @@ -342,6 +352,9 @@ Examples: $foo = pack("i9pl", gmtime); # a real struct tm (on my system anyway) + sub bintodec { + unpack("N", pack("B32", substr("0" x 32 . shift, -32))); + } .fi The same template may generally also be used in the unpack function. .Ip "pipe(READHANDLE,WRITEHANDLE)" 8 3 @@ -1358,6 +1371,15 @@ which will assume a bit vector operation is desired when both operands are strings. This interpretation is not enabled unless there is at least one vec() in your program, to protect older programs. +.Sp +To transform a bit vector into a string or array of 0's and 1's, use these: +.nf + + $bits = unpack("b*", $vector); + @bits = split(//, unpack("b*", $vector)); + +.fi +If you know the exact length in bits, it can be used in place of the *. .Ip "wait" 8 6 Waits for a child process to terminate and returns the pid of the deceased process, or -1 if there are no child processes. |