People that don't write portable C code think that they know 95-100% of the language.
I don't miss the days in the late 90's, early 2000, writing portable C code across multiple compilers from each OS vendor, across all major UNIX flavours and Windows.
Many that think to master C, actually master C in compiler X targeting OS Y.
However I prefer that pain, to the lack of strong typing that C++ offers over C.
But better would be to use something else instead of C and C++, more type safe, without UB and without the wide range of implementation differences and compiler extensions.
I don't miss the days in the late 90's, early 2000, writing portable C code across multiple compilers from each OS vendor, across all major UNIX flavours and Windows.
Many that think to master C, actually master C in compiler X targeting OS Y.