Chapter 19. Structure Conversion

pack template, list

Packs the values in list into a sequence of bytes, using the specified template. Returns this sequence as a string.

unpack template, expr

Unpacks the sequence of bytes in expr into a list, using template.

template is a sequence of characters as follows:

a / A

Byte string, null-/space-padded

b / B

Bit string in ascending/descending order

c / C

Signed/unsigned byte value

d / D

Native double/long double

f / F

Native float/Perl internal float

h / H

Hex string, low/high nybble first

i / I

Signed/unsigned integer value

j / J

Perl internal integer/unsigned

l / L

Signed/unsigned long value

n / N

Short/long in network (big endian) byte order

p / P

Pointer to a null-terminated/fixed-length string

q / Q

Signed/unsigned quad value

s / S

Signed/unsigned short value

u / U

Uuencoded string/Unicode UTF-8 character code

v / V

Short/long in VAX (little endian) byte order

w

A BER compressed integer

x / X

Null byte (skip forward)/Back up a byte

Z / @

Null-terminated string/null fill to position

The size of an integer, as used by i and I, depends on the system architecture. Nybbles, bytes, shorts, longs, and quads are always exactly 4, 8, 16, 32, and 64 bits respectively. Characters s, S, l, and L may be followed by a ! to signify native shorts and longs instead. x and X may be followed by a ! to specify alignment.

Each character, or group of characters between parentheses, may be followed by a decimal number, optionally between [ and ], that will be used as a repeat count; an asterisk ( ...

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