#include <iostream>
#include <assert.h>
#include <vld.h> //visual leak detected
//经visual leak detected测试,工作良好,无内存泄露
using namespace std ;
class base
{
public:
base();
base(int pi);
virtual ~base();
base(base& rhs); //拷贝
base& operator=(const base& rhs); //赋值
void _set(int px, char *pp);
void _print();
private:
int i;
char *p;
};
base::base()
{
i = 0;
p = NULL;
}
base::base(int pi):i(pi)
{
p = NULL;
}
base::~base()
{
delete []p;
}
base::base(base &rhs)
{
*this = rhs;
}
base& base::operator =(const base &rhs)
{
cout<<"base ="<<endl;
if( this==&rhs )
return *this;
if( rhs.p )
{
delete[] p;
p = new char[ strlen(rhs.p)+1 ];
strcpy(p, rhs.p);
}
else
{
p = new char[1];
p[0]='\0';
}
i = rhs.i;
return *this;
}
void base::_print()
{
cout<<"base: "<<endl
<<"i: "<<i<<endl;
if (p)
{
cout<<"p: "<<p<<endl;
}
else
{
cout<<"p: "<<"NULL"<<endl;
}
}
void base::_set(int px, char *pp)
{
i = px;
if(pp)
{
delete[] p;
p = new char[strlen(pp)+1];
strcpy(p, pp);
}
}
/////////////////////////////////////
/////////////////////////////////////
/////////////////////////////////////
class derived:public base
{
public:
derived();
derived(int pi);
derived(derived &rhs);
~derived();
derived& operator=(const derived &rhs);
void _set(int px, char *pp);
void _print();
private:
int i;
char *p;
};
derived::derived()
{
i = 0;
p = NULL;
}
derived::derived(int pi):base(pi),i(pi)
{
p = NULL;
}
derived::derived(derived &rhs)
{
*this = rhs;
}
derived& derived::operator=(const derived &rhs)
{
cout<<"derived = "<<endl;
if( this==&rhs)
return *this;
if( rhs.p)
{
delete []p;
p = new char[ strlen(rhs.p)+1 ];
strcpy(p, rhs.p);
}
else
{
p = new char[1];
p[0] = '\0';
}
i = rhs.i;
//基类赋值
base::operator =(rhs);
return *this;
}
derived::~derived()
{
delete []p;
}
void derived::_print()
{
cout<<"derived: "<<endl
<<"i: "<<i<<endl;
if (p)
{
cout<<"p: "<<p<<endl;
}
else
{
cout<<"p: "<<"NULL"<<endl;
}
}
void derived::_set(int px, char *pp)
{
i = px;
if(pp)
{
delete[] p;
p = new char[strlen(pp)+1];
strcpy(p, pp);
}
}
/////////////////////////////////////
/////////////////////////////////////
/////////////////////////////////////
int main()
{
/* 测试内存泄露情况
base *b1=new base();
base *b2=new base();
derived *d1=new derived();
derived *d2=new derived();
b1->_set(10, "aaaa");
b2->_set(20, "bbbb");
d1->_set(30, "cccc");
d2->_set(40, "dddd");
*d1=*d2;
*b1=*b2;
b1->_print();
delete b1;
delete b2;
delete d1;
delete d2;
*/
//测试基类赋值情况
base *b1;
derived d1(10);
derived d2(20);
d1._print();
b1 = (base*)&d1;
b1->_print();
d1=d2;
b1->_print();
return 0;
}
//犯的错误 1:对char*进行构造函数初始化,这其实是个指针值的赋予,会造成释放的错
//误,并且建议两者要分开
//2:*d1,*d2 ; d1=d2, 对指针直接进行赋值,自然不会调用operator = 函数
//3:在进行operator=时,注意把原来的空间放掉
//4:delete d1,d2,d3;这样愚蠢的表达式
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