Re: [cpp] 初次光临,请多指教

[孙华明]

哦，明白了。
----- Original Message ----- 
From: "Stone Jiang" <2005119 at gmail.com>
To: "C++ Discuss Group" <cpp at codingnow.com>
Sent: Monday, July 10, 2006 4:21 PM
Subject: Re: [cpp] 初次光临,请多指教


> 应该是这个类没有正确拷贝构造函数和赋值函数.
> 这时系统分生成一个按位拷贝的缺省版本.
> 
> 
> xWrapper   w1;
> xWrapper  w2;
> w2 = w1;
> 这时,w1和w2这两个对象的xItem指向位置同时是w2.xItem的地址,原来w1.xItem已经永远不会被系统收回.
> 
> 在析构中,两个对象要析构两次w2.xItem
> 所以系统要崩溃.
> 
> 解决的办法是,实现完整的Big Four函数.或者,禁止用户调用拷贝构造函数和赋值函数/
> 具体做法是把拷贝构造函数和赋值函数放在私有部分.
> 
> 
> On 7/10/06, ling <xl-yc-lzj at necsoft.com.cn> wrote:
> >
> > 今天看了c++对话系列，为什么说下面的类程序会因为内存问题而崩溃呢？
> >
> > #include "xStruct.h" // definition of struct X
> >
> > class xWrapper
> > {
> >     X* xItem;
> > public:
> >     xWrapper() : xItem(new X) { }
> >     ~xWrapper() { delete xItem; }
> >
> >     void dump() { /* dumps xItem to cout */ }
> > };
> >
> > _______________________________________________
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> > Cpp at codingnow.com
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> >
> >
> 
> 
> -- 
> Take care
> Stone Jiang
> blog:  http://blog.csdn.net/FocusOnACE/
> 
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> Cpp at codingnow.com
> http://codingnow.com/mailman/listinfo/cpp

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