最近看一点python的代码，发现struct这个包在处理网络编程上非常强大，pack和unpack函数能很轻松地将数据组包拆包，如下所示：
- #! /usr/bin/env python
- import socket, struct, time, re
- if __name__ == '__main__':
- num1 = 5
- num2 = 10
- str1 = 0x00001000
- str2 = 0x00002000
- cha1 = 3
- cha2 = 65
- pack_res = struct.pack('!HHIIBB', num1, num2, str1, str2, cha1, cha2)
- print "after pack "
- print "pack_res", pack_res
- n1,n2,s1,s2,c1,c2 = struct.unpack("!HHIIBB", pack_res)
- print "after unpack"
- print "n1 = ", n1
- print "n2 = ", n2
- print "s1 = ", s1
- print "s2 = ", s2
- print "c1 = ", c1
- print "c2 = ", c2
- '''''
- after pack
- pack_res
- ??????????...
- after unpack
- n1 = 5
- n2 = 10
- s1 = 4096
- s2 = 8192
- c1 = 3
- c2 = 65
- '''
官方手册有格式参数的说明，摘录如下，其中感叹号表示网络序字节流，H代表无符号短整型，B代表无符号字符，I代表无符号整形。
| Character | Byte order | Size | Alignment |
|---|---|---|---|
| @ | native | native | native |
| = | native | standard | none |
| < | little-endian | standard | none |
| > | big-endian | standard | none |
| ! | network (= big-endian) | standard | none |
| Format | C Type | Python type | Standard size | Notes |
|---|---|---|---|---|
| x | pad byte | no value | ||
| c | char | string of length 1 | 1 | |
| b | signed char | integer | 1 | (3) |
| B | unsigned char | integer | 1 | (3) |
| ? | _Bool | bool | 1 | (1) |
| h | short | integer | 2 | (3) |
| H | unsigned short | integer | 2 | (3) |
| i | int | integer | 4 | (3) |
| I | unsigned int | integer | 4 | (3) |
| l | long | integer | 4 | (3) |
| L | unsigned long | integer | 4 | (3) |
| q | long long | integer | 8 | (2), (3) |
| Q | unsigned long long | integer | 8 | (2), (3) |
| f | float | float | 4 | (4) |
| d | double | float | 8 | (4) |
| s | char[] | string | ||
| p | char[] | string | ||
| P | void * | integer | (5), (3) |