四种不同对象的生存方式（栈、堆、全局、局部静态）

例题1：

class Sample
{
       int x;
public:
      Sample(int a)
       {
              x = a;
              cout << "constructing object: x =" << x << endl;
       }
};
 
void func(int n)
{
       static Sample obj(n);
}
 
int main()
{
       func(1);
       func(10);  //1
       return 0;
 
}

[分析]：题目的考查点，静态对象的创建及执行。类中的静态对象只会执行一次，这是输出上面结果的原因。

[扩展分析]：此种静态对象的题目之前在360面试的时候被问到过，后来在《深入浅出MFC》基础部分讲解C++重要性质之——C++程序的生与死：兼谈构造函数与析构函数部分的示例很能说明问题。

题目2

#include <iostream>
using  namespace std;


 class CDemo
{
public:
       CDemo(const char* str);
       ~CDemo();
       void showObjectName();   //显示对象名。
 
private:
       char name[20];
};
 
 
CDemo::CDemo(const char* str)
{
      strncpy_s(name,str,20);
       cout << "Constructor called for " << name << "\n";
}
 
CDemo::~CDemo()
{
       cout << "Destructor called for " << name << "\n";
};
 
void func()
{
       CDemo LocalObjectInFunc("LocalObjectInFunc"); //5  //10
       static CDemo staticObject("StaticObject"); //6   
       CDemo* pHeapObjectInFunc = new CDemo("HeapObjectInFunc"); //7 //11
       cout << "Inside func" << endl; //8 //12
} //9析构LocalObjectInFunc //13析构LocalObjectInFunc
 
void CDemo::showObjectName()   //显示对象名
{
       cout << name << "\n";
}
 
CDemo GlobalObject("GlobalObject"); //1
 
int main()
{
       CDemo localObjectInMain("LocalObjectInMain");  //2
       CDemo* pHeapObjectInMain = new CDemo("HeapObjectInMain"); //3
 
       cout << "In main, before calling func\n\n\n"; //4
       func();
       cout << "\n\n";                             //13'
 
       func();                 //staticObject静态对象已经存在，不再创建!                                    
       cout << "\n\nIn main, after calling func\n";  //14
 
       //test作用域
       //staticObject.showObjectName();  //error C2065: “staticObject”: 未声明的标识符
       //cout << "In main, after GlobalObject.showObjectName(): ";
       //GlobalObject.showObjectName();
		system("pause");
       return 0;
}//15析构localObjectInMain //16析构staticObject //17析构GlobalObject