str.unpack(format) â anArray
Instance Public methods
Decodes str (which may contain binary data) according to the
format string, returning an array of each value extracted. The format
string consists of a sequence of single-character directives, summarized in
the table at the end of this entry. Each directive may be followed by a
number, indicating the number of times to repeat with this directive. An
asterisk (â*'') will use up all remaining elements.
The directives sSiIlL may each be followed by an underscore
(â_'') or exclamation mark (â!'')
to use the underlying platform's native size for the specified type;
otherwise, it uses a platform-independent consistent size. Spaces are
ignored in the format string. See also Array#pack.
1 2 3 4 5 6 7 8 | "abc \0\0abc \0\0".unpack('A6Z6') #=> ["abc", "abc "]"abc \0\0".unpack('a3a3') #=> ["abc", " \000\000"]"abc \0abc \0".unpack('Z*Z*') #=> ["abc ", "abc "]"aa".unpack('b8B8') #=> ["10000110", "01100001"]"aaa".unpack('h2H2c') #=> ["16", "61", 97]"\xfe\xff\xfe\xff".unpack('sS') #=> [-2, 65534]"now=20is".unpack('M*') #=> ["now is"]"whole".unpack('xax2aX2aX1aX2a') #=> ["h", "e", "l", "l", "o"] |
This table summarizes the various formats and the Ruby classes returned by each.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 | Integer | |Directive | Returns | Meaning----------------------------------------------------------------- C | Integer | 8-bit unsigned (unsigned char) S | Integer | 16-bit unsigned, native endian (uint16_t) L | Integer | 32-bit unsigned, native endian (uint32_t) Q | Integer | 64-bit unsigned, native endian (uint64_t) | | c | Integer | 8-bit signed (signed char) s | Integer | 16-bit signed, native endian (int16_t) l | Integer | 32-bit signed, native endian (int32_t) q | Integer | 64-bit signed, native endian (int64_t) | | S_, S! | Integer | unsigned short, native endian I, I_, I! | Integer | unsigned int, native endian L_, L! | Integer | unsigned long, native endian | | s_, s! | Integer | signed short, native endian i, i_, i! | Integer | signed int, native endian l_, l! | Integer | signed long, native endian | | S> L> Q> | Integer | same as the directives without ">" except s> l> q> | | big endian S!> I!> | | (available since Ruby 1.9.3) L!> Q!> | | "S>" is same as "n" s!> i!> | | "L>" is same as "N" l!> q!> | | | | S< L< Q< | Integer | same as the directives without "<" except s< l< q< | | little endian S!< I!< | | (available since Ruby 1.9.3) L!< Q!< | | "S<" is same as "v" s!< i!< | | "L<" is same as "V" l!< q!< | | | | n | Integer | 16-bit unsigned, network (big-endian) byte order N | Integer | 32-bit unsigned, network (big-endian) byte order v | Integer | 16-bit unsigned, VAX (little-endian) byte order V | Integer | 32-bit unsigned, VAX (little-endian) byte order | | U | Integer | UTF-8 character w | Integer | BER-compressed integer (see Array.pack)Float | |Directive | Returns | Meaning----------------------------------------------------------------- D, d | Float | double-precision, native format F, f | Float | single-precision, native format E | Float | double-precision, little-endian byte order e | Float | single-precision, little-endian byte order G | Float | double-precision, network (big-endian) byte order g | Float | single-precision, network (big-endian) byte orderString | |Directive | Returns | Meaning----------------------------------------------------------------- A | String | arbitrary binary string (remove trailing nulls and ASCII spaces) a | String | arbitrary binary string Z | String | null-terminated string B | String | bit string (MSB first) b | String | bit string (LSB first) H | String | hex string (high nibble first) h | String | hex string (low nibble first) u | String | UU-encoded string M | String | quoted-printable, MIME encoding (see RFC2045) m | String | base64 encoded string (RFC 2045) (default) | | base64 encoded string (RFC 4648) if followed by 0 P | String | pointer to a structure (fixed-length string) p | String | pointer to a null-terminated stringMisc. | |Directive | Returns | Meaning----------------------------------------------------------------- @ | --- | skip to the offset given by the length argument X | --- | skip backward one byte x | --- | skip forward one byte |
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