[saghm]

Syntactically, C++ is a superset of C though, right? I can't think of any C syntax that's not valid C++, but I'm not exactly am expert in either

[minipci1321]

> I can't think of any C syntax that's not valid C++,

enum toto { a = 1 }; enum toto b = 1;

Fixing versions of both standards could bring in more examples (like trailing comma in enums and use of the names reserved in C++, by the C code).

Overall, ironically, as typing is stronger in C++ (which I agree is a non-syntactic change), poor C code (using lots of unjustified casts), will require less modifications to be compiled as C++.

[saghm]

Thanks for the example!

[bstamour]

C supports variable-length stack-allocated arrays, while C++ doesn't. So code like

    void f() {
        int x;
        scanf("%d", &x); // read from user
        int numbers[x]; // dynamic
    }

is legal C, but not C++.

Also, the C "restrict" keyword doesn't exist in C++ either. Add in C's looser typing rules regarding conversions, and C and C++ are basically sibling languages at this point. Their common ancestor language being K&R-era C.

[saghm]

> C supports variable-length stack-allocated arrays, while C++ doesn't. So > code like > > void f() { > int x; > scanf("%d", &x); // read from user > int numbers[x]; // dynamic > }

I just pasted this in a file (and added `#include <cstdio>`) and compiled with g++, and it gave no errors or warnings and produced a *.o file, so maybe it does work?

[bstamour]

That's because gcc supports it as an extension to C++. It's not an official part of the language, and using it in C++ code is therefore not portable across compilers/platforms.

[saghm]

clang++ seems to work as well. I don't have a Windows machine handy to try MSVC, though

[minipci1321]

> I can't think of any C syntax that's not valid C++, enum toto { a = 1 }; enum toto b = 1;

Fixing versions of both standards could bring in more examples (like trailing comma in enums and use of the names reserved in C++, by the C code).

Overall, ironically, as typing is stronger in C++ (which I agree is a non-syntactic change), poor C code (using lots of unjustified casts), will require less modifications to be compiled as C++.