C++ Smart Pointer performance

Question

How much do using smart pointers, particularly boost::shared_ptr cost more compared to bare pointers in terms of time and memory? Is using bare pointers better for performance i

Answer 1

Boost provide different smart pointers. Generally both the memory occupation, which varies in accordance to the kind of smart pointer, and the performance should not be an issue. For a performance comparison you can check this http://www.boost.org/doc/libs/1_37_0/libs/smart_ptr/smarttests.htm.

As you can see only construction, copy and destruction are taken into account for the performance comparison, which means that dereferencing a smart pointer has supposedly the same cost as that of a raw pointer.

The following snippet demonstrates that there's no performance loss by using a shared_ptr<> in place of a raw pointer:

#include 
#include 

int main()
{
#ifdef USE_SHARED_PTR
    std::tr1::shared_ptr i(new int(1));
#else
    volatile int * i = new int(1);
#endif

    long long int h = 0;

    for(long long int j=0;j < 10000000000LL; j++)
    {
        h += *i;
    }

    std::cout << h << std::endl;
    return 0;
}