Question

我用构造函数创建了一个类。

我正在main.cpp中创建 n个个对象。现在，每次创建对象时，都应自动调用构造函数。

但是由于我正在main.cpp中创建此对象，所以我想使用信号来处理“ Ctrl + C”终止。

我这样写main.cpp：

#include <iostream>
#include "Session.hpp"

class Session {
public:
    Session(int _count):count(_count) {
        std::cout << "Create Session " << count << std::endl;
    }
    ~Session() {
        std::cout << "Destroy Session " << count << std::endl;
    }
    Print() {
        cout << "Hello" << endl;
    }
private:
    const int count;
};

void signal_handler(int signal, unsigned int count, **WHAT SHOULD I WRITE HERE**) {
    for (unsigned int del_count = 0; del_count < count; del_count++) {
        **I WANT TO DELETE ALL THE FOO OBJECTS CREATED IN THE MAIN FUNCTION**
    }
}

int main() {
    unsigned int num_of_sessions;
    cin >> num_of_sessions;

    signal(SIGINT, signal_handler, num_of_sessions, **WHAT MORE SHOULD I PASS HERE**);

    unique_ptr<Session> Foo[num_of_sessions];
    unsigned int count = 0; // initialize the counter for sessions

    while (count < num_of_sessions) {
        Foo[count] (new Session(count));
        count++;
    }
    while (true){
        for (count = 0; count < num_of_sessions; count++) {
            Foo[count]->PrintName();
        }
    }
    return 0;
}

我收到此错误消息

错误：与“（std :: unique_ptr）（会话*）”的调用不匹配
Foo [count]（新会话（计数））；

有什么建议吗？

Answer 1

您不需要删除unique_ptr，当变量超出范围时，它们将被销毁。在这种情况下，它将是主要功能的结束。

这就是unique_ptr的重点，您不必照顾内存管理。

如果您只想设置信号并对主函数内部堆栈中分配的对象执行操作，则可以使用这样的指针：

#include <iostream>
#include <csignal>
#include <vector>
#include <atomic>
#include <memory>
#include <chrono>
#include <thread>

std::atomic<bool> end_condition;
class Session {
    public:
    Session(int _count):count(_count) {
        std::cout << "Create Session " << count << std::endl;
    }
    ~Session() {
        std::cout << "Destroy Session " << count << std::endl;
    }
    void printSessionCount() {
        std::cout << "Session count is " << count << std::endl;
    }
    private:
    const int count;
};
std::vector< std::unique_ptr<Session>>* foo_p; // <= Probably not necessary but this is how you would access your variable defined in main in signal handler

void signal_handler(int signal) {
   // You don't have handle clean up of your vector.
   // foo_p->clear(); <= Unnecessary to delete every element of your vector here, since they will be automatically deleted at the end of main
    end_condition.store(false);
}

int main() {
    end_condition.store(true);
    unsigned int num_of_sessions;
    std::cin >> num_of_sessions;

    // register signal SIGINT and signal handler
    signal(SIGINT, signal_handler);

    std::vector< std::unique_ptr<Session> > foo;
    foo_p = &foo; // Make your global pointer points to your pointer created in the main function. Accessing foo_p before the point will result in a segmentation fault since the pointer will be null
   // You may not need this at all depending on what you want to do during in the signal handler

    for(int i = 0; i < num_of_sessions; ++i) {
        // Populate your vector
        foo.emplace_back(new Session(i));
    }

    while (end_condition.load()){
        //Call a function for each vector
        for(int i =0; i < foo.size(); ++i) {
            foo.at(i)->printSessionCount();
        }
         std::this_thread::sleep_for(std::chrono::seconds(1));
    }

    return 0;
}    // vector foo memory will be deleted here

如何使用unique_ptr声明调用构造函数并处理程序终止信号

1 个答案: