Why has the destructor been called only once?

Question

#include <iostream>

using namespace std;

class Test
{
public:
    Test()
    {   
        printf("construct ..\n");
    }   

    ~Test()
    {   
        printf("destruct...\n");
    }   
};

Test Get()
{
    Test t = Test();
    return t;
}

int main(int argc, char *argv[])
{
    Test t = Get();
    return 0;
}

the console output is :

$ g++ -g -Wall -O0 testdestructor.cc
$ ./a.out 

construct ..

destruct...

Answer 1

Its because of copy-elision by the compiler when you return the value from the function. In this case, the copy-elision is called RVO - Return Value Optimization.

See these

• Return Value Optimization
• Copy elision