Question

The comment to this answer got me wondering. I’ve always thought that C was a proper subset of C++, that is, any valid C code is valid C++ code by extension. Am I wrong about that? Is it possible to write a valid C program that is not valid C++ code?

EDIT: This is really similar to, but not an exact duplicate of this question.

Answer 1

In general, yes C code is considered C++ code.

But C is not a proper subset in a strict sense. There are a couple of exceptions.

Here are some valid things in C that are not valid in C++:

int *new;//<-- new is not a keyword in C char *p = malloc(1024); //void * to char* without cast  

There are more examples too, but you get the idea.

I previously wrote a more extensive answer in a similar question here.