Core Function Unpack
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=== Return Value === | === Return Value === | ||
| − | Success: Returns the data | + | Success: Returns the array of data (Even if its only 1 item) unless the flag is set to 1 then it will return a string. |
Failure: Returns empty array. | Failure: Returns empty array. | ||
Revision as of 12:43, 17 November 2011
Unpack( <expression>, <binary-array>, <flag> )
Contents |
Description
Unpack data from a binary array
expression
The format string to use.
binary-array
An binary array of bytes such as one produced by the Pack function.
flag
Optional; Control what is returned options are: 0 = Return an array 1 = Return a string
Return Value
Success: Returns the array of data (Even if its only 1 item) unless the flag is set to 1 then it will return a string.
Failure: Returns empty array.
Remarks
Its worth noting you can cycle through a Binary variable like this :
$binary = Pack("z0", "Hello World!") ; Yes you can get the size of the binary byte array by using UBound just like with arrays println("The binary size is: " . UBound($binary) ) For $i In $binary println( "Byte: " . $i . " | Hex: " . Hex($i) . " | Char: " . Chr($i) ) Next
Example
Convert a string into a binary array and back again:
$arr = Pack("z0", "Hello World!") For $i In $arr println($i) Next $str = Unpack("z0", $arr) println($str)
Convert a dobule into a binary array and back again:
$arr = Pack("d", 777.42) For $i In $arr println($i) Next $str = Unpack("d", $arr) println($str)
Convert a int into a binary array and back again:
$arr = Pack("d", (int)777) For $i In $arr println($i) Next $str = Unpack("d", $arr) println($str)
Convert a string into a hex and back again:
$hex = Join(Unpack("*H", Pack("z0", "Hello World!")), '') println("Hex String: " . $hex) $str = Unpack("z0", Pack("h", $hex)) println("Normal String: " . $str)
To pack two integers in big endian format, you would use this:
$bytes = Pack ("^ii", 1234, 4542);
More Examples:
; The following means: ; Little endian encoding of a Int16, followed by an aligned ; int32 value. $r = Pack("_s!i", 0x7b, 0x12345678); For $i In $r print(Hex($i) . " ") Next ; Prints 7B 0 0 0 80 56 34 12 $bytes = Pack("CCCC", 65, 66, 67, 68) println($bytes) ; Prints 4-byte sequence for "ABCD" $bytes = Pack("4C", 65, 66, 67, 68) println($bytes) ; Prints 4-byte sequence for "ABCD" $bytes = Pack("*C", 65, 66, 67, 68) println($bytes) ; Prints 4-byte sequence for "ABCD" $bytes = Pack("^ii", 0x1234abcd, 0x7fadb007) For $i In $bytes print(Hex($i) . " ") Next println("") ; Result: 12 34 ab cd 7f ad b0 07 ; Encode 3 integers as big-endian, but only provides two as arguments, ; this defaults to zero for the last value. $bytes = Pack("^iii", 0x1234abcd, 0x7fadb007) For $i In $bytes print(Hex($i) . " ") Next println("") ; Result: 12 34 ab cd 7f ad b0 07 00 00 00 00 ; Encode as little endian, pack 1 short, align, 1 int $bytes = Pack("_s!i", 0x7b, 0x12345678); For $i In $bytes print(Hex($i) . " ") Next println("") ; Result: 7b 00 00 00 78 56 34 12 ; Encode a string in utf-8 with a null terminator $bytes = Pack("z8", "hello") For $i In $bytes print(Hex($i) . " ") Next println("") ; Result: 68 65 6c 6c 6f 00 00 00 00 ; Little endian encoding, for Int16, followed by an aligned ; Int32 $bytes = Pack("_s!i", 0x7b, 0x12345678) For $i In $bytes print(Hex($i) . " ") Next println("") ; Result: 7b 00 00 00 78 56 34 12
