[python]理解union__python

不懂資料結構苦啊

union在記憶體中只佔有一塊記憶體空間，空間大小由union中佔位最多的資料類型決定，union在初始化的時候，union的值，由最後一個有效參數決定

'''Created on 2012-9-9@author: jincheng'''from ctypes import *print "aaa:"value = raw_input()v=int(value)vv=long(value)vvv=valueclass aaa(Union):    _fields_=[       ("aaa",c_int),       ("bbb",c_long),       ("ccc",c_char),       ]print "aaaaaaa:%s" %valuea=aaa(v,vv,vvv)print "aaa: %d" %a.aaaprint "bbb: %ld" %a.bbbprint "ccc: %s" %a.ccc

test1

c:\Python27>python D:\jincheng\workspace\GrayHatPython\chapter1.pyaaa:6aaaaaaa:6aaa: 54bbb: 54ccc: 6

test2

c:\Python27>python D:\jincheng\workspace\GrayHatPython\chapter1.pyaaa:66aaaaaaa:66aaa: 13878bbb: 13878ccc: 66

修改

from ctypes import *print "aaa:"value = raw_input()v=int(value)print "v %d" %vprint "bbb:"val=raw_input()vv=long(val)vvv=valueclass aaa(Union):    _fields_=[       ("aaa",c_int),       ("bbb",c_long),       ("ccc",c_char * 6),       ]print "aaaaaaa:%s" %valuea=aaa(v,vv)s=a.aaass=int(s)print "ss %d" %ssprint "aaa: %d" %a.aaaprint "bbb: %ld" %a.bbbprint "ccc: %s" %a.ccc

test

D:\Python27>python d:\demo.pyaaa:66v 66bbb:55aaaaaaa:66ss 55aaa: 55bbb: 55ccc: 7