pack
Pack data into binary string
Syntax
pack ( string $format [, mixed $... ] ) : string
Parameters
format
The format string consists of format codes followed by an optional repeater argument. The repeater argument can be either an integer value or * for repeating to the end of the input data. For a, A, h, H the repeat count specifies how many characters of one data argument are taken, for @ it is the absolute position where to put the next data, for everything else the repeat count specifies how many data arguments are consumed and packed into the resulting binary string.
| Code | Description |
|---|---|
| a | NUL-padded string |
| A | SPACE-padded string |
| c | signed char |
| C | unsigned char |
| d | double (machine dependent size and representation) |
| e | double (machine dependent size, little endian byte order) |
| E | double (machine dependent size, big endian byte order) |
| f | float (machine dependent size and representation) |
| g | float (machine dependent size, little endian byte order) |
| G | float (machine dependent size, big endian byte order) |
| h | Hex string, low nibble first |
| H | Hex string, high nibble first |
| i | signed integer (machine dependent size and byte order) |
| I | unsigned integer (machine dependent size and byte order) |
| J | unsigned long long (always 64 bit, big endian byte order) |
| l | signed long (always 32 bit, machine byte order) |
| L | unsigned long (always 32 bit, machine byte order) |
| n | unsigned short (always 16 bit, big endian byte order) |
| N | unsigned long (always 32 bit, big endian byte order) |
| P | unsigned long long (always 64 bit, little endian byte order) |
| q | signed long long (always 64 bit, machine byte order) |
| Q | unsigned long long (always 64 bit, machine byte order) |
| s | signed short (always 16 bit, machine byte order) |
| S | unsigned short (always 16 bit, machine byte order) |
| v | unsigned short (always 16 bit, little endian byte order) |
| V | unsigned long (always 32 bit, little endian byte order) |
| x | NUL byte |
| X | Back up one byte |
| Z | NUL-padded string |
| @ | NUL-fill to absolute position |
...
Return
Returns a binary string containing data.
Examples
1
<?
$format = "nvc*";
$return = pack($format, 0x1234, 0x5678, 65, 66);
print_r(unpack("c6", $return));
?>
Array
(
[1] => 18
[2] => 52
[3] => 120
[4] => 86
[5] => 65
[6] => 66
)
2
<?
$format = "nvc*";
$return = pack($format, 0x1234, 0x5678, 65, 66);
print_r(unpack("H12", $return));
?>
Array
(
[1] => 123478564142
)
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