Folks seem to enjoy pointing out that I use printf in many of my examples of “modern C++”, as if printf is not really proper C++. Apparently, I should be using cout. The trouble is that cout isn’t exactly modern either. It has been around for as long as I can remember and it certainly doesn’t exemplify modern C++ as envisioned by C++11 and beyond. The oldest C++ textbook on my shelf was printed in 1993 and covers cout. I even posed the question to some C++ historians and they were able to date it back as far as 1989. Therefore, the argument that printf is old and cout is modern doesn’t fly. A truly modern C++ solution would also not be substantially slower than hand-written code. Most printf implementations today provide adequate type checking both at compile time and run time. Visual C++ even provides secure versions that make it quite straightforward to write defensive code quite easily with printf. Go ahead and use cout if you prefer, but don’t claim it’s the modern replacement for printf.
Here’s a slide from my 10 Practical Techniques to Power Your Visual C++ Apps course where I examine the performance of searching and sorting text. I won’t explain the numbers – you can watch the course for that – but it should be evident that cout has a serious performance problem. That analysis was done before James McNellis added some awesome modernization and performance improvements to printf in Visual C++ 2015.