new/delete 和malloc/free 的区别（代码部分）

原理部分可以参见别人的博文

http://www.cppblog.com/Lee/archive/2009/03/09/75990.html

 

声明：

//NewDelete.h
#ifndef _NEWDELETE__H_
#define _NEWDELETE__H_
void TestMallocFree();
void TestNewDelete();
void TestNew();
#endif

实现：

//NewDelete.cpp
#include <stdio.h>
#include <malloc.h>
class CObject
{
public:
    CObject(){
        printf("Destruct0\n");
    }

    ~CObject(){
        printf("ConDestruct0\n");
    }

    void Init(){
        printf("ConDestruct\n");        
    }
    void Destroy(){
        printf("ConDestruct\n");
    }
};

class CMultDestruct
{
public:
    static int c_destruct;
    int m_dat;
    CMultDestruct():m_dat(0)
    {
        c_destruct++;
        printf("没有参数的构造函数,destruct cnt:%d\n",c_destruct);
    }
    CMultDestruct(int a):m_dat(0)//先执行初始化列表,后执行函数体
    {
        c_destruct++;
        m_dat = a;
        printf("带参数的构造函数:m_dat:%d,inpara:%d,destruct cnt:%d\n",m_dat,a,c_destruct);
    }
};
int CMultDestruct::c_destruct = 0;

void TestMallocFree()
{
    CObject* pObject = (CObject*)(malloc(sizeof(CObject)));
      pObject->Init();
     pObject->Destroy();
     free(pObject);
}

void TestNewDelete()
{
    CObject* pObject = new CObject;
    delete pObject;
}

void TestNew()
{
    //无参数的构造
    CMultDestruct* p1= new CMultDestruct();

    //带参数的构造
    CMultDestruct* p2= new CMultDestruct(1);

    //数组的构造和析构
    CMultDestruct* ps1= new CMultDestruct[5];
    delete []ps1;

    //CMultDestruct* ps2= new CMultDestruct[5](1);//错误 编译不过去
    CMultDestruct* ps3[]= {new CMultDestruct(1),new CMultDestruct(2),new CMultDestruct(3),new CMultDestruct(4),new CMultDestruct(5)};
    //delete []ps3;//错误,正确的做法如下
    for(int i=0;i<sizeof(ps3)/sizeof(ps3[0]);i++)
    {
        delete ps3[i];
    }
 
    //依靠操作系统的实例,缺点是只能在函数声明周期结束后才能被回收内存
    CMultDestruct pImp;
    CMultDestruct pImp2 = CMultDestruct(1);

    //静态类的实例
    static CMultDestruct sImp = CMultDestruct(1);
}

示例代码：

    printf("动态内存申请:\n");
    TestMallocFree();
    TestNewDelete();
    printf("测试类的内存申请:\n");
    TestNew();

运行结果：