PHP pack() 函數
定義和用法
pack() 函數把數據裝入一個二進制字符串。
語法
pack(format,args+)
| 參數 | 描述 |
|---|---|
| format | 必需。規定在包裝數據時所使用的格式。 |
| args+ | 可選。規定被包裝的一個或多個參數。 |
format 參數的可能值：
- a - NUL-padded string
- A - SPACE-padded string
- h - Hex string, low nibble first
- H - Hex string, high nibble first
- c - signed char
- C - unsigned char
- s - signed short (always 16 bit, machine byte order)
- S - unsigned short (always 16 bit, machine byte order)
- n - unsigned short (always 16 bit, big endian byte order)
- v - unsigned short (always 16 bit, little endian byte order)
- i - signed integer (machine dependent size and byte order)
- I - unsigned integer (machine dependent size and byte order)
- l - signed long (always 32 bit, machine byte order)
- L - unsigned long (always 32 bit, machine byte order)
- N - unsigned long (always 32 bit, big endian byte order)
- V - unsigned long (always 32 bit, little endian byte order)
- f - float (machine dependent size and representation)
- d - double (machine dependent size and representation)
- x - NUL byte
- X - Back up one byte
- @ - NUL-fill to absolute position
實例
例子 1
<?php
echo pack("C3",80,72,80);
?>
輸出：
PHP
例子 2
<?php
echo pack("C*",80,72,80);
?>
輸出：
PHP
