C++构造函数和析构函数的使用与讲解

class Obj
{
...
public:
   Obj()
   {
     ...
   }
};

class Obj
{
...
public:
   Obj()
   {
    ...
   }
   Obj(int x, int y)
   {
    ...
   }
};

class Obj
{
public:
  ~Obj()
   {
   }
};

#ifndef _OBJECT_H_
#define _OBJECT_H_
struct Student
{
 char name[32];
 int age;
 Student* pNext;
};
class DataObj
{
public:
 DataObj();
 ~DataObj();
 void add(Student* pStu);
 void find(int age);
 void printNode(Student* pNode);
private:
 Student m_head;
};
#endif

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "DataObj.h"
//构造有头链表
DataObj::DataObj()
{
 m_head.pNext = NULL;
}
DataObj::~DataObj()
{
 //指向每个节点的头部
 Student* p = m_head.pNext;
 //释放所有节点
 while(p)
 {
 Student *next = p->pNext;
 free(p);
 p = next;
 }
}
void DataObj::add(Student* pNode)
{
 //指向每个节点的头部
 Student* p = &m_head;
 //通过头节点查找到链表尾部节点
 while (p)
 {
 if (p->pNext == NULL)
 {
  break;
 }
 p = p->pNext;
 }
 //添加节点到尾部
 p->pNext = pNode;
}
void DataObj::find(int age)
{
 //标记是否找到
 bool bFind = false;
 Student* p = &m_head;
 while(p)
 {
 if (p->age == age)
 {
  bFind = true;
  printNode(p);
 }
 p = p->pNext;
 }
 if (!bFind)
 {
 printf("没有找到该age的节点");
 }
}
void DataObj::printNode(Student* pNode)
{
 printf("name = %s, age = %d\n", pNode->name, pNode->age);
}
int main()
{
 //构造节点
 Student* pStu = (Student*) malloc(sizeof(Student));
 strcpy(pStu->name, "aaaa");
 pStu->age = 30;
 pStu->pNext = NULL;
 {
 DataObj dataObj;
 //添加节点
 dataObj.add(pStu);
 //查找节点
 dataObj.find(31);
 }
 return 1;
}