php display data implementation method of 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() Binary data can be parsed 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, which can be separated by slashes. The first parameter table of pack() and unpack() functions is as follows

■a: NULL padding byte string

■A: space-filled byte string

■h: hexadecimal number, low nibble first

■H: hexadecimal number, high nibble Section 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 Is 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 Integer (always 32 bits, big endian)

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

■f: Floating point (machine dependent size and representation )

■ d: double (machine dependent size and representation)

■ x: null byte

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