Results of a recent survey suggest that many devs have a hard time keeping up with changes between each rev of C++.

C++17 before and after table

by Tony Van Eerd

About the article:

Here's a collection of the major changes between C++14 and C++17, with example code for each - typically showing how it may have been written before C++17, and how it can now be written with the new C++17 feature(s).