c++ - STL如何使构造10个不同的队列

Question

如下列代码，

#include <iostream>
#include <queue>

int main() {
    queue<int>* queue_list[10];
    for (int l = 0; l <  10; ++l) {
        queue<int> queue;
        queue_list[l] = &queue;
    }
    for (int i = 0; i < 10; ++i) {
        cout << queue_list[i] << endl;
    }
}

我循环初始化了10个队列，可是我打印出来发现是同一个地址，会互相影响；请问如何可以让10个队列互相独立。

Answer 1

Your queue is declared inside the for loop. Each loop queue is created at the same location and then destroyed by . So you always get the same address. When exiting the loop, all queue will no longer exist. queue_list[]The pointers insideare all illegal.

If you want to create these queue on the stack, queue<int> queue_list[10] you can.

Answer 2

What you write like this is to declare repeatedly in the loop, and the queue is all the same object on the stack. To put new on the heap

#include <iostream>
#include <queue>

int main() {
    std::queue<int>* queue_list[10];
    for (int l = 0; l <  10; ++l) {
        std::queue<int> *queue = new std::queue<int>;
        queue_list[l] = queue;
    }
    for (int i = 0; i < 10; ++i) {
        std::cout << queue_list[i] << std::endl;
    }
}