Constructor called once but destructor called several times when using of boost::thread in c++

Question

I'm using of boost library to create a thread in c++ by boost::thread class.
I have the following class in which defined a void routine (int) as a boost::thread routine :

A class :

class A
{
public:
    // Constructor
    A() { cout << "this is constructor" << endl; }

    void routine(int num)
    {
        for(int i = 0; i < num; i++)
        {
            // do stuffs
            cout << num + i << endl;
            Sleep(1000);
        }
    }

    // Destructor
    ~A() { cout << "this is destructor" << endl; }
};

And main function :

int main()
{
    A a;
    myThread = new boost::thread(&A::routine, a, 6);

    myThread->join();

    return 0;
}

In the main I create an object of A and constructor function is call once, but something is wrong. in this situation the destructor function should be call just once too, but it called several times and the following result is obtained :

this is constructor
this is destructor
this is destructor
this is destructor
this is destructor
this is destructor
this is destructor
this is destructor
6
7
8
9
10
11
this is destructor
this is destructor

Any suggestion?

You are not counting the use of the compiler defined copy constructor. — R Sahu, Apr 13 '19 at 06:59
@RSahu Thanks. My problem solved. I counted the copy constructor and the number of `constructors` and `destructors` are equal... — BattleTested_закалённый в бою, Apr 13 '19 at 07:03
@RSahu but my question is not duplicated like https://stackoverflow.com/questions/10875381/c-why-does-my-destructor-run-twice — BattleTested_закалённый в бою, Apr 13 '19 at 07:07
The question is not but cause of the problem is the same and explanation of the behavior is the same. — R Sahu, Apr 13 '19 at 07:09
Also see [Why is the destructor of the class called twice?](https://stackoverflow.com/q/2627540/608639) — jww, Apr 13 '19 at 07:17
@RSahu but why by calling `boost::thread` one time, create more than one object??? please answer me. — BattleTested_закалённый в бою, Apr 13 '19 at 08:15
`boost::thread` constructor takes its argument by value, if you don't want to create copy you could pass params with `boost::ref` , `boost::cref`, these wrap objects into pointer, and no copies are made. — rafix07, Apr 13 '19 at 16:57

Constructor called once but destructor called several times when using of boost::thread in c++

0 Answers0