PHP pack() 函数
PHP pack() 函数
定义和用法
pack() 函数把数据装入一个二进制字符串。
语法
pack(format,args+)
| 参数 | 描述 |
|---|---|
| format | 必需。规定在包装数据时所使用的格式。 |
| args+ | 可选。规定被包装的一个或多个参数。 |
format 参数的可能值：
- 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
实例
例子 1
<?phpecho pack("C3",80,72,80);?>
输出：
PHP
例子 2
<?phpecho pack("C*",80,72,80);?>
输出：
PHP