PHP implementation of binary data _php example

PHP uses pack () and unpack () to process binary data.

Pack () is used to convert data into binary data using the following methods:

Pack ("LL", 0,1);

Pack ("C", a);

Unpack () can parse binary data into a relational array, which accepts 2 parameters using the following method:

$arr = Unpack ("Chead", $binstream); Read 1th byte

$arr = Unpack ("Chead/c3string/c4number", $binstream); Reads 8 bytes, which can be separated by a slash

The first parameter table for the pack () and unpack () functions is as follows

A:null populated byte string

A: space-filled byte string

H: Hexadecimal number, low four-byte priority

H: Hexadecimal number, high four-byte precedence

C: Signed characters

C: Unsigned characters

S: signed short integer (always 16 bits, machine byte-order)

S: unsigned short integer (always 16 bits, machine byte-order)

N: unsigned short integer (always 16-bit, large-tailed byte-order)

V: unsigned short integer (always 16-bit, small-tailed byte-order)

I: Signed integer (machine-related size and byte order)

I: unsigned integer (machine-related size and byte order)

L: Signed Long Integer (always 32 bits, machine byte-order)

L: unsigned long integer (always 32-bit, machine byte-order)

N: unsigned long integer (always 32-bit, large-tailed byte-order)

V: unsigned long integer (always 32-bit, small-tailed byte-order)

F: Floating point number (machine-relative size and representation)

D: Double precision Number (machine-related size and representation)

x: null bytes

X: Backwards One byte

@: Fill absolute position with null

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