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Diffstat (limited to 'pod/perlfunc.pod')
| -rw-r--r-- | pod/perlfunc.pod | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index 3e791810db..efa7b58c12 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -2754,6 +2754,35 @@ C<"P"> is C<undef>. =item * +The C<"#"> character allows packing and unpacking of strings where the +packed structure contains a byte count followed by the string itself. +You write I<length-item>C<#>I<string-item>. + +The I<length-item> can be any C<pack> template letter, +and describes how the length value is packed. +The ones likely to be of most use are integer-packing ones like +C<"n"> (for Java strings), C<"w"> (for ASN.1 or SNMP) +and C<"N"> (for Sun XDR). + +The I<string-item> must, at present, be C<"A*">, C<"a*"> or C<"Z*">. +For C<unpack> the length of the string is obtained from the I<length-item>, +but if you put in the '*' it will be ignored. + + unpack 'C#a', "\04Gurusamy"; gives 'Guru' + unpack 'a3#A* A*', '007 Bond J '; gives (' Bond','J') + pack 'n#a* w#a*','hello,','world'; gives "\000\006hello,\005world" + +The I<length-item> is not returned explicitly from C<unpack>. + +Adding a count to the I<length-item> letter +is unlikely to do anything useful, +unless that letter is C<"A">, C<"a"> or C<"Z">. +Packing with a I<length-item> of C<"a"> or C<"Z"> +may introduce C<"\000"> characters, +which Perl does not regard as legal in numeric strings. + +=item * + The integer types C<"s">, C<"S">, C<"l">, and C<"L"> may be immediately followed by a C<"!"> to signify native shorts or longs--as you can see from above for example a bare C<"l"> does mean exactly 32 |