<未完>再次研究指针和引用

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原创最新推荐文章于 2026-08-07 21:05:00 发布 754 阅读 AI 写同款· GEO 优化 ›

[Java JVM] Hotspot GC研究- 64位引用指针压缩技术为什么需要指针压缩在上一篇文章 [Java JVM] Hotspot GC研究- 开篇&对象内存布局中介绍对象内存布局时, 曾提到过, 由于在64位CPU下, 指针的宽度是64位的, 而实际的heap区域远远用不到这么大的内存, 使用64bit来存对象引用会造成浪费, 所以应该做点事情来节省资源. 如何做基于以下事实: CPU 使用的虚拟地址是64位的, 访问内存时, 必须使用64位的指针访问内阅读详情

#include <iostream>
using namespace std;
class apple{
public:
	int id;

public:
	apple(int id){
	   this->id = id;
	}
	void operator=(apple tmp){
		this->id = tmp.id;
	}
};
void f1(apple* app){
   app = new apple(101);
}
void f2(apple& app){
   apple* tmp = new apple(101);
   app = *tmp;
}
void f3(apple* &app){
   app = new apple(101);
}
void f4(apple app){
   apple* tmp = new apple(101);
   app = *tmp;
}
int main(){
   apple* app = new apple(100);
   apple app2 = *app;
   //f1(&app2);
   //f3(&app2);报错
   //apple* c = &app2;
   //f3(c);
   f4(app2);
   //app->id
   cout << app2.id << endl;
}
//f1:100
//f2:101
//f3:101
//f4:100
//app2
//f1:100
//f2:101
//f3:错误
//f3:100
//f4:100

#include <iostream>
using namespace std;
class apple{
public:
	int id;

public:
	apple(int id){
	   this->id = id;
	}
	void operator=(apple tmp){
		this->id = tmp.id;
	}
};
void f1(apple* app){
   //app = new apple(101);
	app->id = 101;
}
void f2(apple& app){
   apple* tmp = new apple(101);
   app = *tmp;
}
void f3(apple* &app){
   app = new apple(101);
}
void f4(apple app){
   apple* tmp = new apple(101);
   app = *tmp;
}
int main(){
   apple* app = new apple(100);
   apple app2 = *app;
   //f1(&app2);
   //f3(&app2);报错
   //apple* c = &app2;
   //f3(c);
   //f4(app2);
   //app->id
   f1(app);
   cout << app->id << endl;
}
//这个竟然输出101………………