[C++应用程序性能优化]对象的生命周期

最新推荐文章于 2025-04-19 16:50:25 发布

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本文通过几个具体的C++示例详细介绍了构造函数与析构函数的工作机制，包括静态成员变量的作用域、对象创建与销毁的过程以及拷贝构造函数的调用时机等关键概念。

#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>

class A
{
public:
 A() { printf("A created.\n"); }
 ~A() { printf("A destroyed.\n"); }
};

class B
{
public:
 B() { printf("B created.\n"); }
 ~B() { printf("B destroyed.\n"); }
};

A g_A;
int foo()
{
 printf("\nfoo() ----------------->\n");
 A localA;
 static B localB;
 printf("\nfoo() <-----------------\n");
 return 0;
}

int main()
{
 printf("main() ------------------>\n");

 foo();
 foo();
 printf("\nmain()<----------------\n");
 system("pause");
 return 0;
}




#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>

class A
{
public:
 A() { printf("A created.\n"); }
 ~A() { printf("A destroyed.\n"); }
};

A* createA()
{
 A* p = new A();
 return p;
}

void deleteA(A* p)
{
 delete p;
}

int main()
{
 A *pA = createA();
 pA = createA();
 deleteA(pA);
 system("pause");
 return 0;
}


 

#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>

class A
{
public:
 A() { printf("A created.\n"); }
 A(A& a) { printf("A created with copy\n"); }
 ~A() { printf("A destroyed.\n"); }
};

A foo(A a)
{
 A b;
 return b;
}

int main()
{
 A a;
 a = foo(a);
 system("pause");
 return 0;
}