Implementation method of PHP processing binary data, php processing binary data_PHP tutorial

The implementation method of PHP processing binary data, PHP processing binary data

PHP needs to use pack() and unpack() to process binary data.

pack() is used to convert data into binary data. The usage method is as follows:

pack(“LL”, 0,1);

pack(“C”, a);

unpack() can parse binary data into a relational array. It accepts 2 parameters and is used as follows:

$arr = unpack(“Chead”, $binstream); //Read the first byte

$arr = unpack(“Chead/C3string/C4number”, $binstream); //Read 8 bytes, separated by slashes

The first parameter list of pack() and unpack() functions is as follows

■a: NULL padded byte string

■A: Space-filled byte string

■h: Hexadecimal number, low nibble first

■H: Hexadecimal number, high nibble first

■c: signed character

■C: Unsigned character

■s: signed short (always 16 bits, machine byte order)

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

■n: unsigned short (always 16 bits, big-endian)

■v: unsigned short (always 16 bits, little endian)

■I: Signed integer (machine dependent size and endianness)

■I: unsigned integer (machine dependent size and endianness)

l: signed long (always 32 bits, machine byte order)

■L: unsigned long (always 32 bits, machine byte order)

■N: unsigned long (always 32 bits, big-endian)

■V: unsigned long (always 32 bits, little endian)

■f: floating point number (machine dependent size and representation)

■d: double (machine dependent size and representation)

■x: null byte

■X: Go back one byte

■@: Fill absolute position with NULL

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