C++对象产生和销毁的顺序

恋喵大鲤鱼

发布于 2019-02-22 14:39:42

1.4K0

发布于 2019-02-22 14:39:42

C++中，如果对象是用new操作生成的，那么它的空间被分配在堆（Heap）上，只有显示地调用delete（或delete[]）才能调用对象的析构函数并释放对象的空间。那么，在程序的其他存储区（Data段，Stack）上的对象依据什么样的顺序产生和销毁的呢？

考察如下程序。

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

class A
{
    string name;
public:
    A(string s) 
    {
        name=s;
        cout<<"object "<<name<<" has been created"<<endl;
    }
    ~A(){
        cout<<"object "<<name<<" has been destroyed"<<endl;
    }
};

void func1() 
{
    static A sa1("static_object_1");
}

void func2(){
    static A sa2("static_object_2");
}

int main(int argc,char* argv[])
{
    A la1("local_object_1");
    A la2("local_object_2");
    func1();
    func2();

    getchar();
}
A a1("global_object_1");
A a2("global_object_2");

程序运行结果：

object global_object_1 has been created
object global_object_2 has been created
object local_object_1 has been created
object local_object_2 has been created
object static_object_1 has been created
object static_object_2 has been created
object local_object_2 has been destroyed
object local_object_1 has been destroyed
object static_object_2 has been destroyed
object static_object_1 has been destroyed
object global_object_2 has been destroyed
object global_object_1 has been destroyed

阅读以上程序的时候，注意以下几点：（1）全局对象或全局静态对象不管是在什么位置定义的，它的构造函数都在main()函数之前执行。（2）局部静态对象的构造函数是当程序执行到定义该对象时才被调用。（3）所有在栈（stack）上的对象都比在全局或静态对象早销毁。（4）不管是在栈上的对象，还是全局或静态对象，都遵循这样的顺序：越是先产生的对象越是后被销毁。

参考文献

[1]陈刚.C++高级进阶教程[M].武汉：武汉大学出版社，2008[3.15(P180-P181)]

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原始发表：2015年10月27日，如有侵权请联系 cloudcommunity@tencent.com 删除

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