Are variable length arrays there in c++?

The current C++ standard does not require that compilers support VLAs. However, compiler vendors are permitted to support VLAs as an extension. GCC >= 4.7, for example, does.

It was originally proposed that VLAs would appear in C++14, however the proposal did not succeed. They also, ultimately, did not appear in C++17.

C99 permits VLA, but C++ never permits that, because the performance of VLA is so unfriendly. And in C11, VLA becomes an optional feature.

Before, it's said that VLA would appear at C++17. But now C++17 is published, and no VLA, either. (And it seems C++20 won't have VLA. The recent documents haven't talk about it at all.)

Although the standard doesn't support it, GNU compiler supports it as an extension.