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0 pointsbstamour8y ago0 comments

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.

0 comments

saghm8y ago

> 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?

bstamourOP8y ago

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.

saghm8y ago

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

j / k navigate · click thread line to collapse

0 pointsbstamour8y ago0 comments

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++.

0 comments

saghm8y ago

> 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?

bstamourOP8y ago

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.

saghm8y ago

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

j / k navigate · click thread line to collapse