无法在分配的实例中推送 priority_queue 处的值

Question

谁能解释一下下面代码的问题？谢谢

#include <queue>
#include <stdlib.h>
using namespace std;
struct Person {
    priority_queue<int> pq;
};
int main(void) {
    Person* person = (Person*)malloc(sizeof(Person));
    person->pq.push(1);// error here
    return 0;
}

Answer 1

不要在 C++ 中使用 malloc（如上所述，它只会分配内存），如果可以，请避免使用 new 和 delete。

 #include <queue>
//#include <stdlib.h> <== do not include in C++
#include <memory>

struct Person 
{
    std::priority_queue<int> pq;
};

int main(void) 
{
    Person* person_ptr = new Person();
    person_ptr->pq.push(1);
    delete person_ptr; // with new you have to also write delete or get memory leaks.

    Person person;      // no need to malloc/new, avoid those in C++ as much as you can.
    person.pq.push(1);  

    // Or if you need a pointer do it like this.
    auto person_uptr = std::make_unique<Person>(); 
    person_uptr->pq.push(1);
    // person_uptr's destruction will do the free for us, no memory leaks ;)

    return 0;
}

无法在分配的实例中推送 priority_queue 处的值

Cannot push value at priority_queue in the allocated instance

c++

stl

push

priority-queue