Is there an equivalent of the function _vscprintf for g++? Or can you suggest an alternative way of accomplishing the same goal?

If you want to use _vscprintf() that means you're using ellipsis, which is generally bad mojo in C++. You might want to consider a stream based replacement. That being said, glibc comes with the function vsprintf() in stdarg.h which is approximately equivalent to _vscprintf(). If you have a non-glibc hosted version of gcc, that function may be absent. But on the plus side, MinGW, which is non-glibc hosted does come with _vcsprintf().