C++ placement new keep giving compiling error

Question

Try to use placement new but it kept giving me errors. I remember a while ago, it was working. g++ (ver 4.8.4) on Ubuntu 14.04.

#include 
typed         


        

Answer 1

To make your original code work, you need to add

void* operator new( size_t, strSession * p ) { return p; }

In the old days, before C++ left Bell Labs, C++ had a feature where a constructor could assign to 'this'. The operator new placement syntax was considered an improvement.

Answer 2

To use placement new, you need to have:

#include <new>

Also, you could just as easily have used:

int main(int argc, char *argv[]) {
    char buf[20];
    strSession *q = new (buf) strSession;
    return 0;
}