C++衍生類別建構函式和解構函式的調用順序

對於建構函式 ：  先執行基類的，再執行對象成員的，最後執行衍生類別的

對於解構函式 ：  先執行衍生類別的，再執行對象成員的，最後執行基類的

即 析構順序與構造順序相反，樣本程式如下：

 

#include <iostream>
#include <string>
#include <cstring>
using namespace std;

class base
{
public :
 base ( )
 {
  cout << " constructing base class " << endl;
 }
 ~base()
 {
  cout << " destructing base class " << endl;
 }
};

class base2
{
 int i;
public :
 base2 ( int n)
 {
  cout << " constructing base2 class " << endl;
  i = n;
 }
 ~base2()
 {
  cout << " destructing base2 class " << endl;
 }
 void showi()
 {
  cout << i << endl;
 }
};
class derived : public base
{
 int    j;
 base2 obj;
public :
 derived ( int n) : obj (n)
 {
  cout << " constructing derived class " << endl;
  j = n;
 }
 ~derived( )
 {
  cout << "destructing derived class " << endl;
 }
 void showj()
 {
  cout << j << endl;
 }

};

int  main ()
{
 derived ob(10);
 ob.showj ();
 return EXIT_SUCCESS;
}

結果為 ：

constructing base class

constructing base2 class

constructing derived  class

10

destructing derived class

destructing base2 class

destructing base class

press any key to continue