Re: 答复: [cpp] 初次光临,请多指教

[Stone Jiang]

的确是缺少copy constructor和copy assignment导致的问题,
当对象复制的时候,不会内存泄漏,但会指针悬挂,  在赋值操作的时候,目标对象内部的指针指向的动态分配的内存块失去控制.

xWrapper a ,b;
当a = b的时候,a.xItex = b.xItem,指向的同时相同的地址.
当a.xItem变化是b.xItem也跟着变化.
当a退出作用范围的时候,b.xItem已被系统收回.这时使用b.xItem 可能会系统崩溃.

记住一点,当对象有指针作为成员变量的时候,一定要考虑对象赋值是否必要,如果需要,那copy constructor和copy
assignment不能省略.

需要的时候还要重载new/delete运算符.



On 7/12/06, 孟岩 <myan at csdn.net> wrote:
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> 把你崩溃的程序贴上来。
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> 应该就是由于缺少copy constructor和copy assignment导致的问题而已。
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> ________________________________

>
> 发件人: cpp-bounces at codingnow.com [mailto:cpp-bounces at codingnow.com] 代表 孙华明
> 发送时间: 2006年7月10日 16:09
> 收件人: C++ Discuss Group
> 主题: Re: [cpp] 初次光临,请多指教
>
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> 是啊怎么崩溃的？
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> 没有内存泄露啊，好像也没有空指针访问啊。
>
>
>
> ----- Original Message -----
>
>
> From: ling
>
>
> To: C++ Discuss Group
>
>
> Sent: Monday, July 10, 2006 10:19 AM
>
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> Subject: [cpp] 初次光临,请多指教
>
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> 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？
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> #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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-- 
Take care
Stone Jiang
blog:  http://blog.csdn.net/FocusOnACE/
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