[python]理解union
- 2020 年 1 月 9 日
- 筆記
不懂数据结构苦啊
union在内存中只占有一块内存空间，空间大小由union中占位最多的数据类型决定，union在初始化的时候，union的值，由最后一个有效参数决定
''' Created on 2012-9-9 @author: jincheng ''' from ctypes import * print "aaa:" value = raw_input() v=int(value) vv=long(value) vvv=value class aaa(Union): _fields_=[ ("aaa",c_int), ("bbb",c_long), ("ccc",c_char), ] print "aaaaaaa:%s" %value a=aaa(v,vv,vvv) print "aaa: %d" %a.aaa print "bbb: %ld" %a.bbb print "ccc: %s" %a.ccc
test1
c:Python27>python D:jinchengworkspaceGrayHatPythonchapter1.py aaa: 6 aaaaaaa:6 aaa: 54 bbb: 54 ccc: 6
test2
c:Python27>python D:jinchengworkspaceGrayHatPythonchapter1.py aaa: 66 aaaaaaa:66 aaa: 13878 bbb: 13878 ccc: 66
修改
from ctypes import * print "aaa:" value = raw_input() v=int(value) print "v %d" %v print "bbb:" val=raw_input() vv=long(val) vvv=value class aaa(Union): _fields_=[ ("aaa",c_int), ("bbb",c_long), ("ccc",c_char * 6), ] print "aaaaaaa:%s" %value a=aaa(v,vv) s=a.aaa ss=int(s) print "ss %d" %ss print "aaa: %d" %a.aaa print "bbb: %ld" %a.bbb print "ccc: %s" %a.ccc
test
D:Python27>python d:demo.py aaa: 66 v 66 bbb: 55 aaaaaaa:66 ss 55 aaa: 55 bbb: 55 ccc: 7
