[C/C++ Digestion] – Rule of Three, ¸´ÖÆ¿ØÖÆ
[C/C++ Digestion] – Rule of Three,
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Jason Lee @
http://blog.csdn.net/jasonblog
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2010-04-13
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copy constructor
Rule of Three
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const
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Demo(const Demo &demo){}
¸´Öƹ¹Ô캯Êý´ÓÐèÒªÉÏÀ´¿´ÓÐÁ½ÖÖÇé¿ö£¬Ò»ÊÇÓгÉÔ±ÔÚ¹¹Ô캯ÊýÖзÖÅä×ÊÔ´£¬±ÈÈçÖ¸Õë
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1.
¸ù¾ÝͬÀàÐͶÔÏó³õʼ»¯Ä³Ò»¶ÔÏó£»ÎÒ¸öÈ˾õµÃÔÚÕâÖÖÇé¿öÏ£¬ºÜÈÝÒ×ÊèºöµÄÒ»¸öϸ½ÚÖ®´¦ÊÇ£ºÒ»°ã£¬¶Ô¹¹Ô캯Êý±È½ÏÉúÊèµÄ³ÌÐòԱϰ¹ßµØ¶¨ÒåÒ»¸öĬÈϹ¹Ô캯Êýºó£¬²¢ÇÒÔÚÀïÃæ½øÐÐÖ¸ÕëËùÐè¿Õ¼äµÄ¿ª±ÙºÍ·ÖÅ䣬¾Í»áDZÒâʶµØÒÔΪÒÔºóÿ¸ö¸ÃÀà¶ÔÏó³õʼ»¯Ê±¶¼»áºÏÀíµØÊ×ÏȶÔÖ¸Õë³ÉÔ±½øÐÐÄÚ´æ·ÖÅ䣬Ȼ¶øÈ´Ã»ÓÐ×ã¹»Éî¿ÌµØÒâʶµ½Èç¹ûµ÷ÓÃÁ˸´Öƹ¹Ô캯Êý£¬Ôò²»»áµ÷ÓÃĬÈϺ¯Êý£º
#include <iostream>
using namespace std;
class Demo {
public:
Demo(){ p = new int(1); }
Demo(const Demo &demo){ *p = *demo.p; }//Ö¸Õëp²¢Î´±»·ÖÅä¿Õ¼ä
~Demo(){}
void setP(int v){ *p = v; }
void show(){ cout << *p << endl; }
private:
int *p;
};
int main(){//³ÌÐòÔËÐÐʱ³ö´í
Demo d1;
d1.setP(3);
Demo d2 = d1;//Ö»µ÷Óø´Öƹ¹Ô캯Êý£¬²¢Ã»Óе÷ÓÃĬÈϹ¹Ô캯Êý£¬ËùÒÔÖ¸ÕëδӵÓпռä
return 0;
}
2.
½«¶ÔÏó×÷ΪÆÕͨʵ²Î£»ÕâÖÖÇé¿ö×îÈÝÒ×ÓëÖµ´«µÝµÄÇé¿ö½øÐÐÁªÏ룺´«µÝµÄÊÇÓë±äÁ¿µÈÖµµÄÒ»¸öÁÙʱֵ£¬¶ø·Çͬһ¸ö±äÁ¿¡£Í¬ÑùµÄ£¬ÒÔ¶ÔÏó×÷ΪÆÕͨʵ²Î£¬Ò²ÐèÒª½¨Á¢Ò»¸öÁÙʱ¶ÔÏ󣬾ÍÐèÒªµ÷Óõ½¸´Öƹ¹Ô캯Êý¡£±ÈÈçÒÔÏÂÒ»¶ÎºÁÎÞÒâÒåµÄ´úÂ룺
3.
´Óº¯ÊýÖзµ»ØÒ»¸öÆÕͨ¶ÔÏó£»ÕâÖÖÇé¿öµÄµÀÀíÓëÉÏÒ»ÖÖÇé¿öÒ»Ñù£¬Á½ÖÖÇé¿ö¿ÉÒÔ³öÏÖÔÚÒ»¶Î´úÂëÖУº
Demo Test(Demo demo){
Demo temp;
return temp;
}
4.
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HTTP·ÖΪÇëÇóÐУ¬ÇëÇóÍ·²¿ÒÔ¼°ÇëÇóÄÚÈÝ
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¸øÒ»¶ÎÀý×ÓÄã¾Í»ù±¾Ã÷°×ÁË:
onst CString getString(int i)
{
CString s;
s.Format(_T("%d"), i);
return s;
}
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